TechWiki - User contributions [en-gb]

Coolant

2026-03-17T18:18:53Z

Lithopsian: /* Brands and codes */ many Japanese blue coolants are PHOAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red HOAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT, lobrid OAT, or PHOAT
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 and many other Japanese (blue), Renault Type E (blue), Toyota Super Long life (pink or blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed, although the official Lotus service interval is 4 years.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC, blue) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2/3===
Rover engined cars use the same coolant as the S1. The recommended coolant for Toyota-engined cars is Havoline XLC.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T18:17:35Z

Lithopsian: /* Colours */ blue is increasingly PHOAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red HOAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT, lobrid OAT, or PHOAT
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed, although the official Lotus service interval is 4 years.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC, blue) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2/3===
Rover engined cars use the same coolant as the S1. The recommended coolant for Toyota-engined cars is Havoline XLC.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T18:00:25Z

Lithopsian: /* Colours */ Toyota red is HOAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red HOAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed, although the official Lotus service interval is 4 years.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC, blue) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2/3===
Rover engined cars use the same coolant as the S1. The recommended coolant for Toyota-engined cars is Havoline XLC.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T17:59:28Z

Lithopsian: /* Lotus */ Toyota-Elises

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed, although the official Lotus service interval is 4 years.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC, blue) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2/3===
Rover engined cars use the same coolant as the S1. The recommended coolant for Toyota-engined cars is Havoline XLC.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T17:30:17Z

Lithopsian: /* Elise S1 */ Unipart AFC is (was) blue

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed, although the official Lotus service interval is 4 years.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC, blue) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T17:28:48Z

Lithopsian: /* Elise S1 */ coolant service interval 4 years

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed, although the official Lotus service interval is 4 years.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T17:25:45Z

Lithopsian: /* Brands and codes */ G64 = G65

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (=G64, but pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-03-17T17:22:51Z

Lithopsian: /* Colours */ not always violet (just the concentrate?)

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords sometimes describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Throttle Linkage

2026-02-23T16:10:09Z

Lithopsian: S1 category

[[Image:Throttlelinkage1.jpg|thumb|150px|left]][[Image:Throttlelinkage1a.jpg|thumb|150px|Step1: Removing the baseplate screws|left]]Step 1 Some of you may stumble here because the two screws holding the base plate on can be very tight and unless you are an Ironman which I am not you won't be able to apply enough torque with a normal screwdriver to get the screws undone. I used an AEG torque application device for this step. You can see me removing one of the screws with the AEG on the left hand side.

Step 2 - Yvo's instructions say you should remove the throttle return spring so the base plate can come out
but I found that it was not necessary, so step 2 must only apply to left hand drive cars. You can see the throttle return spring on the right hand side of the photograph.

 
[[Image:Throttlelinkage3.jpg|thumb|150px|Step3|left]]The base plate was lifted away and positioned where I could work on it. I noticed that there has been a lot of scraping going on where the link has been rubbing on the base plate for the last 48,000 miles.
''The black button in the middle of the throttle lever is a "slider button". It is meant to rub on the plate, that's the thin dark rubbed area. When the button wears down, the rest of the lever may start to rub, which is the wider rubbed area in your picture. The button can be replaced and will greatly improve the smoothness of the throttle movement in these cases. DeRoure says £1.03 factory order. Without a good button, there is extra strain on the pivot bushes and nylon washers and the whole lot will start to flex again more quickly than it should.''
 
[[Image:Throttlelinkage4.jpg|thumb|150px|Step4: I decided to disconnect the throttle cable side first so a Phillips screwdriver on one side and a 7mm socket on the other.|left]]
[[Image:Throttlelinkage4a.jpg|thumb|150px|And these are the components that came apart.|left]]
[[Image:Throttlelinkage5.jpg|thumb|150px|Step5|left]]Step 5 - My smallest open ended spanner is 8mm, which was too big for the next step because the ball joint required a 6mm open ended spanner on the back side of the linkage.

I used long nosed pliers to grasp the back of the ball joint and used an 7mm socket to undo the nut. It wasn't a problem because the nut was only nipped up.

See the photograph in step 8 showing the position of the pliers.

 
[[Image:Throttlelinkage6.jpg|thumb|150px|Step6: The throttle cable came out easily enough. I just pulled the cable assembly apart to expose the inner core and the cable slid through the slot in the base plate.|left]]
[[Image:Throttlelinkage6a.jpg|thumb|150px|6a: The assembly was then free from the car. I noticed the pivot nut was loose. I hadn't touched it and I don't know how long it has been like that.|left]]
[[Image:Throttlelinkage6b.jpg|thumb|150px|6b: Dismantling the original linkage from the base plate was easy, no tools needed here for me.|left]]

 
[[Image:Throttlelinkage7a.jpg|thumb|150px|Step7a: The next series of photographs show the new linkage being assembled to the base plate using a combination of new steel washers and an original steel washer for extra clearance. My base plate has a stud, so I didn't need to use the screw that was supplied in the kit. First of all a new M4X12 washer went on.|left]]
[[Image:Throttlelinkage7b.jpg|thumb|150px|7b: But after completing this part of the assembly I found the new linkage still rubbed on the base plate so I took it all apart again and added one of the original M5 washers because I did not have another M4X12 washer available.|left]]
[[Image:Throttlelinkage7c.jpg|thumb|150px|7c: then the top washer went on.|left]]

 
[[Image:Throttlelinkage7d.jpg|thumb|150px|7d: Followed by the nut. Fortunately I have small fingers and this step could be tricky if you've got Arnold Scharzenegger sized hands.|left]]
[[Image:Throttlelinkage7f.jpg|thumb|150px|left]]7e: The nut only needed to be nipped up otherwise I would have snapped the stud or crushed the bearing.

After nipping up the nut I checked to make sure the linkage moved freely. This is when I found that I needed two washers at the bottom, because the linkage still rubbed on the base plate with only one washer.

I also checked to make sure the nut was tightened up correctly so the linkage moved freely but was not loose at the same time.

 
[[Image:Throttlelinkage8.jpg|thumb|150px|Step8|left]]Step 8 - Then it was time to fit it all back together. Here is the photograph that shows the pliers clamping the ball joint and nipping up the nylock nut. This is what I was referring to back in step 5.

I originally used the middle hole for the standard throttle option as shown in this photograph, but I later changed my mind and moved it to the inner hole for the quick throttle option.

The photograph in step 9f shows the linkage connected in the inner position for the quick throttle option.

 
[[Image:Throttlelinkage9a.jpg|thumb|150px|9a: The throttle cable assembly went back on.|left]]
[[Image:Throttlelinkage9b.jpg|thumb|150px|9b|left|Step9b: Then it was time to start assembling the throttle cable washer stack. This was the most complicated part of the whole procedure and great care had to be taken to assemble the components in the right order.

The washer stack splits into lower, middle and upper sub-assemblies.]]
[[Image:Throttlelinkage9c.jpg|thumb|150px|9c: I assembled the washer stack making sure to grease the two original nylon washers. This photograph shows the middle layer in position.|left]]
[[Image:Throttlelinkage9d.jpg|thumb|150px|9d|left|9d: Then the top layer of the washer stack went on.]]

 
[[Image:Throttlelinkage9e.jpg|thumb|150px|9e: Then I gently nipped the nylock nut up. I had to use an adjustable spanner because I do not possess a 7mm open ended spanner.|left]]
[[Image:Throttlelinkage9f.jpg|thumb|150px|left|9f]]9f: All ready for the base plate to be bolted back on.

This photograph has been updated since I originally fitted the linkage.

I have now connected the throttle linkage to the inner hole and it is set up to give the quick throttle option.

For the standard setting (middle hole) I did not have to make any changes to either the throttle stop or at the throttle body end. See the photograph in step 8.

For quick throttle setting (inner hole) I had to adjust the throttle stop by approximately 10mm, but I found that I did not need to make any adjustments at the throttle body end.

 
[[Image:Throttlelinkage10a.jpg|thumb|150px|Step10a: Yvo supplied two bolts for the base plate and they are a much better idea than the screws.|left]]
[[Image:Throttlelinkage10b.jpg|thumb|150px|10b: I just nipped up the bolts and job done. Notice in this photograph the linkage was set to the normal middle position.|left]]
[[Image:Throttlelinkage11.jpg|thumb|150px|Step11: Reconnect the throttle return spring and we are done.|left]]

 
[[Image:Throttlelinkage12.jpg|thumb|150px|Here are the tools I used plus my trusty AEG. The sockets are 7mm & 8mm.|left]]
[[Image:Throttlelinkage13.jpg|thumb|150px|And here are the parts left over. I fitted one of the original steel washers in step 7 to get extra clearance between the base plate and the throttle linkage.|left]]
I checked to make sure that everything moved freely and started the car up. I noticed an instant improvement in the smoothness of the throttle. It's one of the best and cheapest modifications that I have done to my car.

 
==Correct nut:washers:bolt assembly==
[[Image:ThrottlelinkageLatestStack.jpg|left]]
Now.. as you might notice, I've added a small M4 washer in the stack (standard M4 washer). I've done this to prevent any locking action between the thick nylon ring and the throttle linkage.
It's not absolutely necessary (if it's moving, it's moving) but it gives just a little more freedom to move, so precautionary action..)

[[Category:S1]]
[[Category:Interior]]
[[Category:Engine]]
[[Category:Air Induction]]

Coolant

2026-02-11T15:36:18Z

Lithopsian: /* Colours */ violet or pink

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard, although Comma/Halfords describe their G30 as violet
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-02-11T15:31:33Z

Lithopsian: PHOAT not really similar to lobrid HOAT despite the acronym

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology, often called '''Lobrid''' to indicate it being an older technology than hybrids such as P-OAT and Si-OAT. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''P-OAT/PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-02-11T15:18:47Z

Lithopsian: /* Brands and codes */ G05 not common over here, but mention what makes it different

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with sodium benzoate and nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green, with silicates), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-02-11T14:45:27Z

Lithopsian: /* Corrosion inhibitors */ sodium benzoate

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, often sodium benzoate rather than a carboxylate, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-22T15:23:35Z

Lithopsian: /* Colours */ green/yellow

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are pale and yellowish)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-22T14:56:37Z

Lithopsian: /* Colours */ some exceptions

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone), or plain OAT (eg. many trucks)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT (some POAT "green" coolants are a bit yellowish, eg. Mazda FL22)
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard (note that OEM Toyota coolant for very old models is red and IAT)
*'''Pink''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard, but Japanese (eg. Toyota) pink coolant is PHOAT
*'''Violet''' or '''lilac''': usually Si-OAT or PSi-OAT, to G12++ or G12 EVO standard
*'''Purple''': glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese), or Si-OAT (BMW/Toyota HT-12)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-21T15:42:00Z

Lithopsian: /* Brands and codes */ move "VW G11 TL 774C" to IAT, although most commercial products meeting the standard are now HOAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard
*'''Pink''', sometimes called '''violet''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard
*'''Purple''': very similar colour to some pink/violet, Glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': VW G11 TL 774C (blue), Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-21T15:35:23Z

Lithopsian: /* Corrosion inhibitors */ list format

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.
*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper. Early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, designed for very long service life but somewhat sensitive to use conditions such as hard water. PSi-OAT is relatively new, but becoming common in European engines.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard
*'''Pink''', sometimes called '''violet''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard
*'''Purple''': very similar colour to some pink/violet, Glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-21T15:32:13Z

Lithopsian: /* Colours */

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours, but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

Based on the colour alone, you might be able to take a guess at what the coolant is, but no guarantees:
*'''Orange''': almost always equivalent to GM Dex-Cool, 2-EHA-based
*'''Yellow''': G05-type lobrid ("heavy duty"), or "universal" (eg. Prestone)
*'''Yellow-green''': probably Renault type D, used to be plain OAT, now Si-OAT
*'''Red''': usually plain OAT, sometimes 2-EHA-based, often more complex carboxylic acids or mixtures, to G12 or G12+ standard
*'''Pink''', sometimes called '''violet''': usually an OAT that is safe to mix with other types of coolant, may be Si-OAT or PSi-OAT, to G12+, G12++, or G12 EVO standard
*'''Purple''': very similar colour to some pink/violet, Glycerin-based Si-OAT to G13 standard
*'''Blue''', '''blue-green''': may be IAT or lobrid OAT (common for European and Japanese OEM coolants)
*'''Green''': may be IAT or P(H)OAT (usually Japanese)

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-21T15:06:05Z

Lithopsian: /* Brands and codes */ PSA blue

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red or pink for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48), Citroen/Peugeot/Opel/G33 (blue)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-20T15:38:01Z

Lithopsian: /* Brands and codes */ not quite the same thing

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red or pink for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-19T16:26:02Z

Lithopsian: /* Colours */ OAT coolants increasingly pink

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red or pink for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (= Comma Super Longlife Red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-19T16:06:21Z

Lithopsian: /* Brands and codes */ BMW coolants

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW LC-87 (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (= Comma Super Longlife Red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), BMW LC-18 (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-19T15:30:40Z

Lithopsian: /* Brands and codes */ ECP purple has glycerin, remove obsolete and rare CG40

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW OEM (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (= Comma Super Longlife Red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple, with glycerin), Havoline QFC (red, with glycerin), new BMW OEM (green), Glysantin G40 (violet), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-19T15:27:29Z

Lithopsian: /* Corrosion inhibitors */

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

===Mixing===
It is generally recommended not to mix different coolants even if they are the same colour, although more modern types are increasingly becoming safe to mix with anything.

The "classic" IAT coolants (eg. G11) should never be mixed with the first-generation "plain" OAT coolants (eg. G12). OAT coolants were then improved (ie. G12+, G30, etc) so that they could be safely mixed with older IAT coolants and the original OAT coolants, albeit potentially with some loss of protection length. These were further developed to Si-OAT and PSi-OAT coolants, which are also generally safe to mix with most older coolants. Mixing coolants of radically different colours may produce an unpleasant-looking brown result.

HOAT, PHOAT, etc., may not be compatible with other types, and there are many coolants that don't fit cleanly into any of these categories. Again the safest advice is never to mix different types.

Although VW G13 and other coolants containing glycerol contain a different combination of antifreezes, it is usually safe to mix them with any other type.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW OEM (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (= Comma Super Longlife Red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple), Havoline QFC (red, with glycerin), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-19T15:16:03Z

Lithopsian: /* Brands and codes */ tweaks

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''': Comma Super Coldmaster, previously Classic (blue), Halfords Silicate (= Comma Super Coldmaster), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''': VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW OEM (blue), Comma/Glysantin G48 (blue/green), Halfords NAP-free (= Comma G48)
**'''PHOAT''': Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Halfords OAT (= Comma Super Longlife Red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''': VW G12++ TL 774G (pink), VW G13 TL 774J (purple, with glycerin), ECP Triple QX Purple (purple), Havoline QFC (red, with glycerin), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple), new Renault Type D (yellow-green)
*'''PSi-OAT''': VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2026-01-18T20:19:01Z

Lithopsian: /* Brands and codes */ updates with some newer products

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but mostly these are a few basic types:
*'''IAT''', Comma/Glysantin Classic (blue), Comma/Glysantin G48 (blue/green, also contains some organic acids), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G05 (yellow, with nitrites) BMW OEM (blue)
**'''PHOAT''', Honda Type 2 (blue), Renault Type E (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma Super Longlife Red (red), Comma/Glysantin G30 (violet), Glysantin G33 (blue/green), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), ECP Triple QX Orange (orange), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), old Renault Type D (yellow-green)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple), new Renault Type D (yellow-green)
*'''PSi-OAT''', VW G12EVO (pink), Glysantin G64 (green), Glysantin G65 (pink)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Replace the steering rack

2026-01-09T15:37:18Z

Lithopsian: fix some sizes

{{Infobox Timetools
|time = 1 hour to remove rack
|tools = 17mm deep socket / 17 mm spanner to release track rod end, 13mm socket, 17mm socket, ratchet, numerous extension bars, 13mm spanner, 32mm spanner (actually 1.25"), 36mm spanner, 5.5mm allenkey, chisel and hammer (to remove rivnut), drill, 2.5mm and 3mm drill bits, vice
}}

Reading the factory manual will have you believing that it's just undo a couple of bolts and bosh, out it comes.

Err, no. Be prepared to be very uncomfortable:

==Removal==
===S1===
First, loosen the front wheel nuts then jack up the front of the car and place on axle stands. Leave a good amount of space at least on one side as you need room to withdraw the rack.

Remove the front wheels.

Now you need to split the track rod ends from the steering arms. Slacken the nuts off to the end of the thread. At this point, it's worth giving the nut a whack upwards with a copper mallet, as this is sometimes enough to free the joint without reaching for your balljoint splitter. If this doesn't work, you're best to use a scissor-type splitter to free the joint.

Now, with both track rod ends released you need to free the bottom steering column UJ from the rack pinion. To do this, first mark the rack pinion in relation to the bottom UJ. I used a dab of tippex (cos it has a handy brush in the lid!). This will help you get the two parts joind back together again afterwards in such a way that hopefully the steering wheel still points in the right direction! Now remove the bottom pinch bolt (13mm) from the bottom UJ. You'll need to get a 13mm spanner on the nut to stop it turning with the bolt.

Now you can remove the 4 bolts that hold the steering rack to the bulkhead. There's two on the bulkhead on the passenger side, and 2 on the bulkhead on the driver's side. The bottom ones need a 13mm socket, the top ones are 17mm socket. I used 2 12" extensions and a 6" extension on the sockets so I could sit in the seats and do it in relative comfort without being upside down in the footwells. Once you've cracked the bolts off and start undoing them, you may find that they're quite hard to turn until they're almost out. This is because they are coated in threadlock and is quite normal.

WIth the bolts out, you should be able to wiggle the rack towards the front of the car a bit, and then wiggle the bottom steering column UJ so that it comes off the rack pinion and you can swing it out of the way.

I then pulled out the rubber grommet around the hole in the bulkhead that the pinion comes through, as this will give you a bit more room in a minute.

Theory goes you should now be able to push the rack towards the front of the car so the pinion clears the bulkhead hole, then slide the rack out.

However, no amount of wiggling back and forth worked on mine. The problem is a rivnut on the front face of the steering rack channel that prevents the rack moving far enough forwards to clear the bulkhead. If you look in the front services compartment, you'll see it just above the outlet from the heater motor. This rivnut isn't needed on right hand drive cars.

I used a sharp chisel to knock the front face off it (in the front services compartment). Then a long screwdriver and a healthy whack to the back of it down the steering rack channel got rid of it.

You should now be able to get in the footwell and tilt the steering rack pinion upwards and it should just clear the hole in the bulkhead. Then just withdraw the rack along the channel.

===S2===
No different to S1 described above for me, apart from there is no need to remove the rivnut, just ask for someone to help you twist it out, it will come.

==Reconditioning==
[[File:Elise Steering rack exploded.jpg|thumb|Exploded diagram for rack with plastic bushes]]
The rack is made by [http://www.titan.uk.net Titan Motorsport], and they will sell all parts to the public on the condition of a £25 minimum order value. And to be honest, they are very helpful too!

I removed my rack as there was play, which I suspected to be the nylon cups at the inner end of each track rod.

I ordered 2 of the cups (£3.50 each), 2 of the springs that sit behind the cups (£ ), 2 of the locking pins that lock the cups to the locking nuts (£ each), and 2 gaitors (£4.50 each).

[From Titan Motorsport, March 2007: A1161611200A3 - £3.35EA - Nylon shoes, A1161610900A3 - 52p - Spring, A1161916700A3 - 28p - Locking Pin. Note: There is a minimum charge fee of £25]

This seems to be the most common cause of play in the rack.

You will need to source grease to re-build your rack. The "rocol MTS1000" is now know as "rocol Sapphire hi-pressure bearing grease" and the "scheerol mpt2 grease" is actually called "spheerol mp2". [A recent thread reports Titan use MTS1000 which is slightly different from the Sapphire product and still available. Spheerol MP2 has been replaced by Spheerol EPL2.] I sourced this from RS but there are other places that sell them. Note 400g is a lot but that was all they had at the time I ordered.
RS Stock No. Qty Unit Price Goods Value Description
198-3136 1 £2.82 £2.82 Spheerol MP2 bearing grease,400gm
330-6288 1 £14.15 £14.15 Sapphire hi-pressurebearing grease,400gm
288-4793 1 £6.00 £6.00 Pocket spring balance w/hook & ring,30kg
Running Total £22.97
Delivery charge £4.95
VAT £4.19 Order total £32.11

Start by removing the cable ties that hold the gaitors on and sliding the gaitors back to the track rod ends (I left the track rod ends in situ, the theory being the tracking wouldn't be too far out when I put it back together).

This exposes the inner ends of the track rods and the cup joint that they sit in.

You will see that the cup joint has a locknut. Between the lock nut and cup joint body there is a small locking pin (roll pin) that needs to be carefully drilled out (using a 2.5 / 3mm drill bit).

Once the locking pin it removed, it should be possible to (carefully) clamp the rack bar in a vice and undo the locknut using a 32mm spanner.

Once the locknut is released, the cup joint will unscrew from the end of the rack.

Remove the cup joint noting the nylon cup and spring that are in there.

Repeat for the other track rod.

Before reassembly (using new sockets) you need to hone the new sockets to the ball surfaces using a light grinding compound. If this is not done the required load setting will be lost within a few hundred miles.

Upon reassembly the two joints should be tightened to a point where a load of 3 to 4 Kg, applied 152mm down the track control arm from the centre of the ball in the joint (ie right near the end), is required to move it. Lock at this point, re-drill, and pin. A centre punch on the end of the locking pin will spread it slightly, securing it.

At this point, I'd noticed that my rack preload seemed far to loose, in that I could turn the pinion shaft with just my finger and thumb, and that when I did this the rack, to my mind, sounded "noisy". There was also one point in the travel where it went "tight".

I made the decision to strip down the rack and re-lube it.

First step in doing this is to remove the pinion. To do this, first undo the Rack Bar Thrust Pad bolt locking nut using a 36mm spanner, then back out the thrust pad bolt using a 5.5mm allen key. Then remove the circlip that holds the pinion assembly in. You can then gently tap out the pinion, for example by mounting the pinion in a vice and gently tapping the housing with a rubber mallet. It doesn't need very much force at all. The pinion will come out with a bearing still attached. This will need to be pressed off if you want to replace it.

Carefully withdraw the rack from the end of the rack body. Finally you can push out the second bearing and the alloy blanking plate. Finger pressure is enough.

You can then carefully withdraw the rack from the end of the rack body.

After a bit of cleaning and degreasing, I found that the internals were pretty much fine, with the exception of a marked tooth on the rack which was causing the tight spot I'd noticed. I just dressed this with a fine file.

Upon reassembly the Rack Bar Thrust Pad should be adjusted to give a preload that allows a horizontaly mounted rack to be pulled along its entire length by a force of 50 - 70 N.

Here you find some pictures of a dismantled rack: http://silverdreamracer.de/steeringrack/index.html

==Re-fitting==

If you slacken both the upper and lower steering column intermediate shaft universal joint cotter bolts, you can get sufficient axial play to ease re-assembly of the bottom joint onto the rack spline with the rack already bolted in place. Once loosened, the upper joint has an amount of axial slack on the intermediate shaft to allow for any installation tolerance

Note: If, for whatever reason, you remove the bottom joint from the end of the intermediate shaft, take care when reassembling that the orientation of the joint is correct to the shaft. The cotter bolt clearance is not a complete revolution in the manner of the pinion spline, so orientation is critical to getting the bolt inserted. Hard to spot when operating by feel down in the footwell!

[[Category:DIY]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]

Coolant

2025-12-22T20:41:08Z

Lithopsian: /* Elise S1 */ clarify HOAT usage

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
**'''PHOAT''', Honda Type 2 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)
*'''PSi-OAT''', Glysantin G64 (green, is this just G48 with a different anti-freeze?)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. Modern OAT coolants ("pink", G12+/++, G30, etc) are more forgiving about being mixed with other types. A HOAT coolant (Unipart AFC) was briefly listed as the official coolant for the K-series in the MGF around 2000. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2025-10-10T20:32:04Z

Lithopsian: /* Brands and codes */

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
**'''PHOAT''', Honda Type 2 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)
*'''PSi-OAT''', Glysantin G64 (green, is this just G48 with a different anti-freeze?)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. HOAT coolants have never been recommended for the K-series engine. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2025-10-10T20:30:20Z

Lithopsian: /* Brands and codes */ Glysantin G64

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
**'''PHOAT''', Honda Type 2 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)
*'''PSi-OAT''', Glysantin G64 (green)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. HOAT coolants have never been recommended for the K-series engine. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2025-10-10T20:25:24Z

Lithopsian: /* Corrosion inhibitors */ PSi-OAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''' and '''PSi-OAT'''. P-OAT coolants are found in many Japanese brands, while PSi-OAT is used in some European brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
**'''PHOAT''', Honda Type 2 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. HOAT coolants have never been recommended for the K-series engine. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2025-10-10T20:15:01Z

Lithopsian: /* Brands and codes */ Honda Type 2 really an old technology, not comparable to modern P-OAT coolants

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''', but are relatively uncommon in the UK. P-OAT coolants are found in many Japanese brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
**'''PHOAT''', Honda Type 2 (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. HOAT coolants have never been recommended for the K-series engine. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2025-10-10T20:14:33Z

Lithopsian: /* Corrosion inhibitors */ P-OAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''P-OAT''', but are relatively uncommon in the UK. P-OAT coolants are found in many Japanese brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
**'''PHOAT''', Honda Type 2 (blue)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. HOAT coolants have never been recommended for the K-series engine. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Coolant

2025-10-10T20:03:32Z

Lithopsian: /* Corrosion inhibitors */ HOAT

Coolant is a liquid circulated through the engine and radiator to keep the engine cool. Water is excellent for extracting heat from the engine, but on its own it has a low boiling point, can freeze in cold weather, and causes rapid corrosion of most metals. Therefore it needs an additive to raise the boiling point, lower the freezing point, and prevent corrosion. The additive is generically called coolant, or sometimes just antifreeze. The chemicals used to provide the antifreeze properties are completely independent of those that inhibit corrosion.

==Antifreeze==
Over 90% of concentrated coolant is a polyol, a chemical like an alcohol but with multiple hydroxyl groups instead of the one that alcohols have, and is used to raise the boiling point and lower the freezing point when mixed in to water. Almost all coolants use one or more of three chemicals to provide the antifreeze effect:
*'''Ethylene glycol''': most modern coolants have only ethylene glycol. It is acutely toxic and sweet, which means it is dangerous for children, pets, and wildlife if spilled in the open, but it is cheap and effective.
*'''Propylene glycol''': started to become popular as a less toxic alternative to ethylene glycol, but now uncommon. Modern coolants usually use bittering agents to make ethylene glycol unpalatable.
*'''Glycerol''': sometimes mixed with ethylene glycol, it is a less toxic and more environmentally friendly antifreeze.

Pure ethylene glycol has a freezing point of -12C, which is not low enough for reliable use in the UK. When mixed with water, the freezing point becomes much lower, below -50C at certain concentrations. Most coolants are formulated to be mixed with approximately 50% water for protection to around -37C. Propylene glycol has a lower freezing point. Glycerol is a viscous liquid at room temperature and freeze at 18C, so it must be used in mixtures with other antifreezes and water.

On the whole there is nothing much to worry about. Coolants all have much the same antifreeze regardless of anything else. Choose one with glycerol if you really want to be eco, although it will still be mostly ethylene glycol.

==Corrosion inhibitors==
There are many different chemicals used as corrosion inhibitors in engine coolants. These make up less than 10% of the coolant, with over 90% being the antifreeze. There are two main classes of corrosion inhibitor, IAT and OAT, but with a bewildering array of combinations, proprietary formulations, names, and colours.

*'''IAT''', Inorganic Acid Technology. Not actually acids, these are salts of inorganic acids, usually quite alkaline, such as amines, nitrites, phosphates, and silicates. These are the traditional corrosion inhibitors, effective for all metals, and have an engine service life of up to 2 years or 30,000 miles. Some downsides are sludging and rusting from as they quickly lose effectiveness, and water pump damage from silicate precipitation.
*'''HOAT''', Hybrid Organic Acid Technology. A confusing term originally used for coolants with inorganic inhibitors that also contained some organic inhibitors, designed to extend the short service life of pure IAT coolants. The term is now sometimes applied to modern coolants such as the silicated OAT group, but these are a very different set of inhibitors.*'''OAT''', Organic Acid Technology. Again, not acids, but salts of organic acids, such as carboxylates, sebacates, and 2-EHA. These give good protection to ferrous metals and aluminium alloys, but poor for "yellow" metals which use solders. They have a longer service life, typically quoted at 5 years or 100,000 miles. These are not safe for use in older engines which contains brass or copper, early versions in the US were dogged by reports of corrosion and engine damage, and one of the inhibitors (2-EHA) has been implicated in damage to silicone-based seals and gaskets. Many modern formulations do not use 2-EHA or have very low levels.
*'''Si-OAT''', Silicate Organic Acid Technology. "Universal" coolants, safe to be mixed with any other coolant. These are now added to many new European cars.
* Other types, such as '''POAT''', but are relatively uncommon in the UK. POAT coolants are found in some Japanese brands.

In general, different coolants with IAT inhibitors, including HOAT coolants, cannot be safely mixed and systems must be flushed when changing from one type to the other. Many OAT coolants can be mixed and the Si-OAT coolants are considered "universal" and can be safely added to systems containing older coolants, although mixing with other types can reduce their effectiveness.

==Identification==
===Colours===
Coolants or antifreezes are usually dyed a strong colour. Originally this was an almost-fluorescent green for easy identification. Later formulations with different corrosion inhibitors were then dyed different colours., but a universal system has never been adopted. Colours vary for the same chemical makeup between brands and in different regions of the world, and the same colours may be used for different chemical makeups.

In the UK in 2018, common colours are blue for IAT and red for OAT, but brand-specific or HOAT coolants may be pink, blue, or yellow, and there is a purple coolant based on glycerol. The original green is not usually seen in the UK any more, although Renault make a fluorescent green coolant that is effectively the same as "orange" long life coolant.

===Brands and codes===
Coolant colour is not a reliable guide to what is actually in the coolant, so it is important both to check what is already in the system and what a new product is. Mixing certain coolant types can produce sludge or thickening, or simply reduce the effectiveness and lifetime. Different manufacturers and car brands use their own or semi-standard codes, but there are only a few basic types in the UK:
*'''IAT''', Comma/Glysantin Classic (blue), Halfords Silicate (blue), ECP Triple QX Blue (blue), Granville Subzero (blue), Bluecol 2yr (blue)
*'''HOAT''',VW G11 TL 774C (blue), Comma/Glysantin G48 (blue/green), BMW OEM (blue)
*'''OAT''', VW G12 TL 774D (red), VW G12+ TL 774F (pink), Comma/Glysantin G30 (red), Glysantin G33 (blue), Glysantin G34 (orange), Halfords OAT (red/pink), ECP Triple QX Red (red), Havoline XLC (orange), Granville Zerocol (red), Bluecol 5yr (red), Renault Type D (green)
**'''PHOAT''', Honda Type 2 (blue)
*'''Si-OAT''', VW G12++ TL 774G (pink), VW G13 TL 774J (purple), ECP Triple QX Purple (purple), Havoline QFC (red), new BMW OEM (green), Glysantin G40 (violet), Glysantin CG40 (purple)

==Lotus==

===Elise S1===
The Elise S1 contains a Rover K-series cast aluminium engine. The Elise S1 owner's handbook recommends only using Unipart Superplus, which was green, and a change interval of two years. Unipart Superplus is no longer available, but similar non-OAT coolants are. The "official" Xpart coolant for the K-series engine is now a red OAT coolant, available [https://www.eliseparts.com/products/show/84/608/lotus-approved-engine-coolant/ at EliseParts]. Many S1's have been switched to the red OAT type at some stage of their lives, which should last approximately 5 years before needing to be changed.

Either IAT or OAT coolants can be used in the Elise S1. The important thing is not to mix them, and to flush the system if changing from one to the other. HOAT coolants have never been recommended for the K-series engine. Check the levels regularly and refresh at the recommended interval.

===Elise S2===
Rover engined cars use the same coolant as the S1.

===Evora===
The recommended coolant for the Evora is red PETRONAS Paraflu Up (previously orange Havoline XLC), an OAT coolant. The change interval is four years. USA?

==See also==
[[Organic Acid Technology]]

== Further reading ==
*[http://en.wikipedia.org/wiki/Antifreeze Antifreeze] at Wikipedia

[[Category:Engine Cooling]]

Exhaust silencers for Elise S1, Exige S1, 340R

2025-09-29T16:11:36Z

Lithopsian: /* Larini */ urls for each backbox

==Elise S1==

===OEM Standard Elise S1===
{{Infobox_Exhaust |
| image = OEM_Exhaust_S1.jpg
| Material = Mild Steel
| Weight = 20kg
| dB =
| Price = £405.99+vat
| Suppliers = Lotus(Unipart / Janspeed)
| Web =
| Notes = Silencer Lotus Code A111S0001F. Tail pipes B111S0063F/B111S0032F (LH/RH)

}}

===OEM Elise S1 111S / Sport 160===
{{Infobox_Exhaust |
| image = OEM_Exhaust_S1_111S.jpg
| Material = Mild Steel
| Weight = 20kg
| dB =
| Price = discontinued - silencer(£112.72+vat) and RH pipe(£114.84+vat) still available
| Suppliers = Lotus(Unipart / Janspeed)
| Web =
| Notes = Silencer Lotus Code A111S0059F. Tail pipes A111S0060F/A111S0061F(LH/RH). Very small difference on tail pipes tips compared to standard. Also, inner pierced pipe slightly protrudes.

}}

===HANGAR 111 Signature Series===
Official website - [http://www.hangar111.com/ Hangar 111]

====Signature Sports Exhaust - Elise S1 Twin Round Tailpipes====
{{Infobox_Exhaust |
| image = elise-s1-signature.jpg
| Material = Stainless Steel
| Weight = Less Than Standard
| dB = 92-96db
| Price = From £315+vat
| Suppliers = Hangar 111 Lotus Performance
| Web = [http://www.hangar111.com/web-store/212-elise-s1-exige-mk1-sports-exhaust-stainless-steel.html Click Here]
| Notes = Stainless Steel Sports exhaust system for the Elise S1 with round tailpipes. Noise level is dependant on state of tune, but you can expect an average of around 94-97Db in most applications.

}}

===BTB Exhausts===
Official website - [http://www.racecar.co.uk/btb/ BTP]

====Twin Round====
{{Infobox_Exhaust |
|
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = BTB
| Web = [http://www.racecar.co.uk/btb Click Here]
| Notes = Stainless steel performance systems. BTB silencers for Lotus Elise have been designed to maximise performance with minimum weight in keeping with the spirit of Lotus design. Sound quality has been specifically tuned to retain a sporty appeal while remaining within tolerable levels for everyday use.
}}

===Bastuck===
Official website - [http://www.bastuck.de/ Bastuck]

====Twin Round====
{{Infobox_Exhaust |
| image = Bastuck_S1.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = Bastuck
| Web = [https://shop.bastuck.de/modern/de/c/sportauspuff-i-performance-katalysator/lotus/elise/elise-bis-bj-2001/sportauspuffanlage-2?categoryID=3247 Click Here]
| Notes = Cat Back
}}

===Magnex===
Official website - [http://www.magnexexhausts.com/ Magnex]

====Twin 3" Round====
{{Infobox_Exhaust |
| image = Magnex.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £399.99
| Suppliers = Magnex
| Web = [http://www.magnexexhausts.com/fullsystems/details.asp?id=102 Click Here]
| Notes = Cat Back
}}DISCONTINUED

===Yoshimura===
Official website - [http://www.kawahara-motorsport.com/ KMS]
====Cyclone====
{{Infobox_Exhaust |
| image = Cyclone.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = Kawahara Motor Sport (KMS)
| Web = [http://www.lotuscars.co.jp/yoshimura/exige/cyclone.html Click Here]
| Notes = Cat Back or Full System
}}

Official website - [http://www.kawahara-motorsport.com/ KMS]
====Cyclone Carbonfibre Wrapped====
{{Infobox_Exhaust |
| image = KMS4.jpg
| Material = Stainless Steel/Carbonfibre
| Weight =
| dB =
| Price = ￥３２８,０００
| Suppliers = Kawahara Motor Sport (KMS)
| Web = [http://www.lotuscars.co.jp/yoshimura/elise/4.htm Click Here]
| Notes = Cat Back or Full System
}}

Official website - [http://www.kawahara-motorsport.com/ KMS]
====Racing Cyclone====
{{Infobox_Exhaust |
| image = Racing-cyclone.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = Kawahara Motor Sport (KMS)
| Web = [http://www.lotuscars.co.jp/yoshimura/exige/racing-cyclone.html Click Here]
| Notes = The exhaust will NOT bolt to the stock cat. You must order the complete system.
}}

===Moto Concept===
Official website - [http://www.moto-concept.de/en/index.php Moto Concept]
====Racing Cup double tip sports exhaust====
{{Infobox_Exhaust |
| image = Bild.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = 650 EUR
| Suppliers = Moto Concept
| Web = [http://www.moto-concept.de/en/autos/lotus/elise1/artikel_elise1_detail.php?item_id=15231 Click Here]
| Notes = Cat Back
}}

===Janspeed===
Official website - [http://www.janspeed.com/ Janspeed]
====Round====
{{Infobox_Exhaust |
| image = Elise-S1-silencer-100.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £349.99
| Suppliers = PTP
| Web =
| Notes = Cat Back
Twin 76mm Back Slashed Round Tails
}}

Official website - [http://www.janspeed.com/ Janspeed]
====Sports (OEM Elise Sport 135 / Sport 190 - optional for Sport 160)====
{{Infobox_Exhaust |
| image = Janspeed-steel-sports.jpg
| Material = Mild Steel
| Weight = 9kg
| dB =
| Price = discontinued
| Suppliers = Lotus(Janspeed)
| Web =
| Notes = Lotus OEM sports exhaust, gain ~6BHP (Lotus Code A111S0037S)
}}

Official website - [http://www.janspeed.com/ Janspeed]

====Roadsport====
{{Infobox_Exhaust |
| image = Roadsport.gif
| Material = Stainless Steel
| Weight =
| dB =
| Price = £350 inc VAT
| Suppliers = PTP
| Web = [http://www.ptp-ltd.co.uk/shop/ProductDetails.aspx?productID=537 Click Here]
| Notes = Cat Back

A bit noisy if used with a cat pipe and Janspeed 4-2-1 manifold. It has a nasty resonance at 3,300rpm - and that is 80 mph in an S1!
I have now added a silenced cat pipe (£99 from Geary).
}}

Official website - [http://www.janspeed.com/ Janspeed]

====Supersport Round====
{{Infobox_Exhaust |
| image = S1-janspeed-supersport.jpg
| Material = Stainless Steel
| Weight = 8Kg
| dB =
| Price = £399.66 inc VAT
| Suppliers = PTP
| Web = [http://www.ptp-ltd.co.uk/shop/ProductDetails.aspx?productID=825 Click Here]
| Notes = Cat Back
Twin 70mm Round Tails.
A pain to fit, offside hanger bolts are above the silencer box and almost impossible to get a spanner on.
}}

Official website - [http://www.janspeed.com/ Janspeed]

====Supersport Oval====
{{Infobox_Exhaust |
| image = Supersport_Oval.jpg
| Material = Stainless Steel
| Weight = 8.8kg
| dB =
| Price = £351.33 inc VAT
| Suppliers = PTP
| Web = [http://www.ptp-ltd.co.uk/shop/ProductDetails.aspx?productID=575 Click Here]
| Notes = Cat Back
}}

===Raceline===
Official website - [http://www.raceline.co.uk/ Raceline]
====Repackable====
{{Infobox_Exhaust |
| image = Mk2mufreplo.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £495 plus VAT
| Suppliers = Raceline
| Web = [http://www.raceline.co.uk/lotuseliseframes.htm Click Here]
| Notes = Cat Back
7" Stainless Steel Exhaust Silencer Assembly Repackable
}}

Official website - [http://www.raceline.co.uk/ Raceline]
====Non Repackable====
{{Infobox_Exhaust |
|
| Material = Stainless Steel
| Weight =
| dB =
| Price = £350 plus VAT
| Suppliers = Raceline
| Web = [http://www.raceline.co.uk/lotuseliseframes.htm Click Here]
| Notes = Cat Back
7" Stainless Steel Exhaust Silencer Assembly Non Repackable
}}

Official website - [http://www.raceline.co.uk/ Raceline]

====4 into 1====
{{Infobox_Exhaust |
| image = Kit6a.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = Four Branch Primary Set - Stainless Steel £291.40 plus VAT

Four into One Exhaust Collector - Stainless Steel £242.26 plus VAT

Cat Replacement Pipe £69.00 plus VAT
| Suppliers = Raceline
| Web = [http://www.raceline.co.uk/lotuseliseframes.htm Click Here]
| Notes = Cat Back or Entire System. Well built system. Nice rumble, not too loud on a standard engine. With Raceline 160 kit & cat pipe, passes noise restrictions at Goodwood and Bedford
}}

===Eliseparts===
Official website - [http://www.eliseparts.com/shop/index.php Eliseparts]
====High Flow Sports Exhaust S1 & Exige====
{{Infobox_Exhaust |
| image = Exhaust-box1_MED.jpg
| Material = Stainless Steel
| Weight = 6kg
| dB =
| Price = £399.44 Inc. VAT
| Suppliers = Eliseparts
| Web = [http://www.eliseparts.com/shop/index.php?main_page=product_info&cPath=118&products_id=391 Click Here]
| Notes = Cat Back
Only requires 2 rubber mounts
}}

===Bell & Colvill===
Official website - [http://www.bell-colvill.co.uk/ Bell & Colvill]
====Sports====
{{ Infobox_Exhaust |
| image = LOTAC05104.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £349.96 inc VAT
| Suppliers = Bell & Colvill
| Web = [http://www.bell-colvill.co.uk/LotusShop/Details.asp?Id=LOTAC05104# Click Here]
| Notes = Cat Back
Order Code : LOTAC05104
}}

===Quicksilver===
Official website -

[http://www.quicksilverexhausts.com/ Quicksilver Exhausts]

or [http://www.lotusexhausts.com/ Lotus Exhausts]
====Super Sport====
{{ Infobox_Exhaust |
| image = Qselises1supersport.jpg
| Material = Stainless steel
| Weight =
| dB = Appx 98 on Std Exige
| Price = £475 Inc. VAT
| Suppliers = Hangar 111
| Web = [http://www.hangar111.com/ckshop.php?item=405&ret=http%3A%2F%2Fwww.hangar111.com%2Fckshop.php%3Fpage%3D1%26category%3D22 Click Here]
| Notes = Cat Back
Twin round tail pipes
}}

===KOMO TEC===
Official website - [http://www.komo-tec.com/index.php KOMO TEC]
====Stainless steel rear silencer Komo-Sport for Elise MK1====
{{Infobox_Exhaust |
| image = 371_0.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = 769 EUR
| Suppliers = KOMO TEC
| Web = [http://www.komo-tec.com/product_info.php/products_id/371 Click Here]
| Notes = Cat Back
The tailpipes are in 2x 70mm diameter with a perforated tube inside.
}}

===Milltek===
Official website - [http://www.millteksport.com/ Milltek]
====Sports====
{{ Infobox_Exhaust |
| image = Milltek_S1.jpg
| Material =
| Weight =
| dB =
| Price =
| Suppliers =
| Web =
| Notes = Cat Back
Dual 76.2mm Meteor
}}

===Larini===
Official website - [http://www.larinisystems.com/ Larini]
====Club Sport====
{{ Infobox_Exhaust |
| image = ELISES1CLUB-t.jpg
| Material = Stainless Steel
| Weight =
| dB = 100dB Static with a CRP on an otherwise standard S1
| Price = £296.00
| Suppliers = Larini
| Web = [https://www.larinisystems.com/collection/lotus/elise-s1/larini-club-sport-exhaust-system Click Here]
| Notes = Cat Back
}}

Official website - [http://www.larinisystems.com/ Larini]
====Sports S1 & Exige====
{{ Infobox_Exhaust |
| image = LS1015-t.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £350.00
| Suppliers = Larini
| Web = [https://www.larinisystems.com/collection/lotus/elise-s1/larini-sports-exhaust-system Click Here]
| Notes = Cat Back
}}

===Blueflame===
Official website - [http://www.blueflameperformance.com/contact.asp Blueflame]
====Sports====
{{Infobox_Exhaust |
| image = Lotuselise_mk1ex.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £295.00 inc.VAT plus £12 UK postage and packing
| Suppliers = [http://www.moto-build.com/ Motobuild]
| Web = [http://www.moto-build.com/mainsite/lotuselise_mk1ex.html Click Here]
| Notes = Cat Back
This is not one of those loud systems that drive you mad and get you refused at trackdays, this has a lovely note without being obtrusive, if you want LOUD this is not it!
}}

==340R==
===Janspeed===
Official website - [http://www.janspeed.com/ Janspeed]
====Carbonfibre Wrapped====
{{Infobox_Exhaust |
|
| Material = Carbonfibre wrapped silencer
| Weight = 10kgs
| dB =
| Price =
| Suppliers =
| Web =
| Notes = Cat Back
}}

===Blueflame===
Official website - [http://www.blueflameperformance.com/contact.asp Blueflame]
====Titanium====
{{Infobox_Exhaust |
| image = 340rtitanium.jpg
| Material = Titanium
| Weight = 5.4Kgs
| dB =
| Price =
| Suppliers =
| Web =
| Notes = Cat Back
}}

===KOMO TEC===
Official website - [http://www.komo-tec.com/index.php KOMO TEC]
====Sportauspuff Edelstahl Komo-Sport 340R====
{{Infobox_Exhaust |
| image = 369_0.jpg
| Material =
| Weight =
| dB =
| Price = 899 EUR
| Suppliers = KOMO TEC
| Web = [http://www.komo-tec.com/product_info.php/products_id/369 Click Here]
| Notes = Cat Back
}}

[[Category:Exhaust]]
[[Category:Lotus Elise]]
[[Category:S1]]

Exhaust silencers for Elise S1, Exige S1, 340R

2025-09-29T16:06:59Z

Lithopsian: /* Twin Round */ use a url that is still live, from the official website although not a shop

==Elise S1==

===OEM Standard Elise S1===
{{Infobox_Exhaust |
| image = OEM_Exhaust_S1.jpg
| Material = Mild Steel
| Weight = 20kg
| dB =
| Price = £405.99+vat
| Suppliers = Lotus(Unipart / Janspeed)
| Web =
| Notes = Silencer Lotus Code A111S0001F. Tail pipes B111S0063F/B111S0032F (LH/RH)

}}

===OEM Elise S1 111S / Sport 160===
{{Infobox_Exhaust |
| image = OEM_Exhaust_S1_111S.jpg
| Material = Mild Steel
| Weight = 20kg
| dB =
| Price = discontinued - silencer(£112.72+vat) and RH pipe(£114.84+vat) still available
| Suppliers = Lotus(Unipart / Janspeed)
| Web =
| Notes = Silencer Lotus Code A111S0059F. Tail pipes A111S0060F/A111S0061F(LH/RH). Very small difference on tail pipes tips compared to standard. Also, inner pierced pipe slightly protrudes.

}}

===HANGAR 111 Signature Series===
Official website - [http://www.hangar111.com/ Hangar 111]

====Signature Sports Exhaust - Elise S1 Twin Round Tailpipes====
{{Infobox_Exhaust |
| image = elise-s1-signature.jpg
| Material = Stainless Steel
| Weight = Less Than Standard
| dB = 92-96db
| Price = From £315+vat
| Suppliers = Hangar 111 Lotus Performance
| Web = [http://www.hangar111.com/web-store/212-elise-s1-exige-mk1-sports-exhaust-stainless-steel.html Click Here]
| Notes = Stainless Steel Sports exhaust system for the Elise S1 with round tailpipes. Noise level is dependant on state of tune, but you can expect an average of around 94-97Db in most applications.

}}

===BTB Exhausts===
Official website - [http://www.racecar.co.uk/btb/ BTP]

====Twin Round====
{{Infobox_Exhaust |
|
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = BTB
| Web = [http://www.racecar.co.uk/btb Click Here]
| Notes = Stainless steel performance systems. BTB silencers for Lotus Elise have been designed to maximise performance with minimum weight in keeping with the spirit of Lotus design. Sound quality has been specifically tuned to retain a sporty appeal while remaining within tolerable levels for everyday use.
}}

===Bastuck===
Official website - [http://www.bastuck.de/ Bastuck]

====Twin Round====
{{Infobox_Exhaust |
| image = Bastuck_S1.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = Bastuck
| Web = [https://shop.bastuck.de/modern/de/c/sportauspuff-i-performance-katalysator/lotus/elise/elise-bis-bj-2001/sportauspuffanlage-2?categoryID=3247 Click Here]
| Notes = Cat Back
}}

===Magnex===
Official website - [http://www.magnexexhausts.com/ Magnex]

====Twin 3" Round====
{{Infobox_Exhaust |
| image = Magnex.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £399.99
| Suppliers = Magnex
| Web = [http://www.magnexexhausts.com/fullsystems/details.asp?id=102 Click Here]
| Notes = Cat Back
}}DISCONTINUED

===Yoshimura===
Official website - [http://www.kawahara-motorsport.com/ KMS]
====Cyclone====
{{Infobox_Exhaust |
| image = Cyclone.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = Kawahara Motor Sport (KMS)
| Web = [http://www.lotuscars.co.jp/yoshimura/exige/cyclone.html Click Here]
| Notes = Cat Back or Full System
}}

Official website - [http://www.kawahara-motorsport.com/ KMS]
====Cyclone Carbonfibre Wrapped====
{{Infobox_Exhaust |
| image = KMS4.jpg
| Material = Stainless Steel/Carbonfibre
| Weight =
| dB =
| Price = ￥３２８,０００
| Suppliers = Kawahara Motor Sport (KMS)
| Web = [http://www.lotuscars.co.jp/yoshimura/elise/4.htm Click Here]
| Notes = Cat Back or Full System
}}

Official website - [http://www.kawahara-motorsport.com/ KMS]
====Racing Cyclone====
{{Infobox_Exhaust |
| image = Racing-cyclone.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price =
| Suppliers = Kawahara Motor Sport (KMS)
| Web = [http://www.lotuscars.co.jp/yoshimura/exige/racing-cyclone.html Click Here]
| Notes = The exhaust will NOT bolt to the stock cat. You must order the complete system.
}}

===Moto Concept===
Official website - [http://www.moto-concept.de/en/index.php Moto Concept]
====Racing Cup double tip sports exhaust====
{{Infobox_Exhaust |
| image = Bild.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = 650 EUR
| Suppliers = Moto Concept
| Web = [http://www.moto-concept.de/en/autos/lotus/elise1/artikel_elise1_detail.php?item_id=15231 Click Here]
| Notes = Cat Back
}}

===Janspeed===
Official website - [http://www.janspeed.com/ Janspeed]
====Round====
{{Infobox_Exhaust |
| image = Elise-S1-silencer-100.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £349.99
| Suppliers = PTP
| Web =
| Notes = Cat Back
Twin 76mm Back Slashed Round Tails
}}

Official website - [http://www.janspeed.com/ Janspeed]
====Sports (OEM Elise Sport 135 / Sport 190 - optional for Sport 160)====
{{Infobox_Exhaust |
| image = Janspeed-steel-sports.jpg
| Material = Mild Steel
| Weight = 9kg
| dB =
| Price = discontinued
| Suppliers = Lotus(Janspeed)
| Web =
| Notes = Lotus OEM sports exhaust, gain ~6BHP (Lotus Code A111S0037S)
}}

Official website - [http://www.janspeed.com/ Janspeed]

====Roadsport====
{{Infobox_Exhaust |
| image = Roadsport.gif
| Material = Stainless Steel
| Weight =
| dB =
| Price = £350 inc VAT
| Suppliers = PTP
| Web = [http://www.ptp-ltd.co.uk/shop/ProductDetails.aspx?productID=537 Click Here]
| Notes = Cat Back

A bit noisy if used with a cat pipe and Janspeed 4-2-1 manifold. It has a nasty resonance at 3,300rpm - and that is 80 mph in an S1!
I have now added a silenced cat pipe (£99 from Geary).
}}

Official website - [http://www.janspeed.com/ Janspeed]

====Supersport Round====
{{Infobox_Exhaust |
| image = S1-janspeed-supersport.jpg
| Material = Stainless Steel
| Weight = 8Kg
| dB =
| Price = £399.66 inc VAT
| Suppliers = PTP
| Web = [http://www.ptp-ltd.co.uk/shop/ProductDetails.aspx?productID=825 Click Here]
| Notes = Cat Back
Twin 70mm Round Tails.
A pain to fit, offside hanger bolts are above the silencer box and almost impossible to get a spanner on.
}}

Official website - [http://www.janspeed.com/ Janspeed]

====Supersport Oval====
{{Infobox_Exhaust |
| image = Supersport_Oval.jpg
| Material = Stainless Steel
| Weight = 8.8kg
| dB =
| Price = £351.33 inc VAT
| Suppliers = PTP
| Web = [http://www.ptp-ltd.co.uk/shop/ProductDetails.aspx?productID=575 Click Here]
| Notes = Cat Back
}}

===Raceline===
Official website - [http://www.raceline.co.uk/ Raceline]
====Repackable====
{{Infobox_Exhaust |
| image = Mk2mufreplo.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £495 plus VAT
| Suppliers = Raceline
| Web = [http://www.raceline.co.uk/lotuseliseframes.htm Click Here]
| Notes = Cat Back
7" Stainless Steel Exhaust Silencer Assembly Repackable
}}

Official website - [http://www.raceline.co.uk/ Raceline]
====Non Repackable====
{{Infobox_Exhaust |
|
| Material = Stainless Steel
| Weight =
| dB =
| Price = £350 plus VAT
| Suppliers = Raceline
| Web = [http://www.raceline.co.uk/lotuseliseframes.htm Click Here]
| Notes = Cat Back
7" Stainless Steel Exhaust Silencer Assembly Non Repackable
}}

Official website - [http://www.raceline.co.uk/ Raceline]

====4 into 1====
{{Infobox_Exhaust |
| image = Kit6a.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = Four Branch Primary Set - Stainless Steel £291.40 plus VAT

Four into One Exhaust Collector - Stainless Steel £242.26 plus VAT

Cat Replacement Pipe £69.00 plus VAT
| Suppliers = Raceline
| Web = [http://www.raceline.co.uk/lotuseliseframes.htm Click Here]
| Notes = Cat Back or Entire System. Well built system. Nice rumble, not too loud on a standard engine. With Raceline 160 kit & cat pipe, passes noise restrictions at Goodwood and Bedford
}}

===Eliseparts===
Official website - [http://www.eliseparts.com/shop/index.php Eliseparts]
====High Flow Sports Exhaust S1 & Exige====
{{Infobox_Exhaust |
| image = Exhaust-box1_MED.jpg
| Material = Stainless Steel
| Weight = 6kg
| dB =
| Price = £399.44 Inc. VAT
| Suppliers = Eliseparts
| Web = [http://www.eliseparts.com/shop/index.php?main_page=product_info&cPath=118&products_id=391 Click Here]
| Notes = Cat Back
Only requires 2 rubber mounts
}}

===Bell & Colvill===
Official website - [http://www.bell-colvill.co.uk/ Bell & Colvill]
====Sports====
{{ Infobox_Exhaust |
| image = LOTAC05104.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £349.96 inc VAT
| Suppliers = Bell & Colvill
| Web = [http://www.bell-colvill.co.uk/LotusShop/Details.asp?Id=LOTAC05104# Click Here]
| Notes = Cat Back
Order Code : LOTAC05104
}}

===Quicksilver===
Official website -

[http://www.quicksilverexhausts.com/ Quicksilver Exhausts]

or [http://www.lotusexhausts.com/ Lotus Exhausts]
====Super Sport====
{{ Infobox_Exhaust |
| image = Qselises1supersport.jpg
| Material = Stainless steel
| Weight =
| dB = Appx 98 on Std Exige
| Price = £475 Inc. VAT
| Suppliers = Hangar 111
| Web = [http://www.hangar111.com/ckshop.php?item=405&ret=http%3A%2F%2Fwww.hangar111.com%2Fckshop.php%3Fpage%3D1%26category%3D22 Click Here]
| Notes = Cat Back
Twin round tail pipes
}}

===KOMO TEC===
Official website - [http://www.komo-tec.com/index.php KOMO TEC]
====Stainless steel rear silencer Komo-Sport for Elise MK1====
{{Infobox_Exhaust |
| image = 371_0.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = 769 EUR
| Suppliers = KOMO TEC
| Web = [http://www.komo-tec.com/product_info.php/products_id/371 Click Here]
| Notes = Cat Back
The tailpipes are in 2x 70mm diameter with a perforated tube inside.
}}

===Milltek===
Official website - [http://www.millteksport.com/ Milltek]
====Sports====
{{ Infobox_Exhaust |
| image = Milltek_S1.jpg
| Material =
| Weight =
| dB =
| Price =
| Suppliers =
| Web =
| Notes = Cat Back
Dual 76.2mm Meteor
}}

===Larini===
Official website - [http://www.larinisystems.com/ Larini]
====Club Sport====
{{ Infobox_Exhaust |
| image = ELISES1CLUB-t.jpg
| Material = Stainless Steel
| Weight =
| dB = 100dB Static with a CRP on an otherwise standard S1
| Price = £296.00
| Suppliers = Larini
| Web = [http://www.larinisystems.com/catalogue.php Click Here]
| Notes = Cat Back
}}

Official website - [http://www.larinisystems.com/ Larini]
====Sports S1 & Exige====
{{ Infobox_Exhaust |
| image = LS1015-t.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £350.00
| Suppliers = Larini
| Web = [http://www.larinisystems.com/catalogue.php Click Here]
| Notes = Cat Back
}}

===Blueflame===
Official website - [http://www.blueflameperformance.com/contact.asp Blueflame]
====Sports====
{{Infobox_Exhaust |
| image = Lotuselise_mk1ex.jpg
| Material = Stainless Steel
| Weight =
| dB =
| Price = £295.00 inc.VAT plus £12 UK postage and packing
| Suppliers = [http://www.moto-build.com/ Motobuild]
| Web = [http://www.moto-build.com/mainsite/lotuselise_mk1ex.html Click Here]
| Notes = Cat Back
This is not one of those loud systems that drive you mad and get you refused at trackdays, this has a lovely note without being obtrusive, if you want LOUD this is not it!
}}

==340R==
===Janspeed===
Official website - [http://www.janspeed.com/ Janspeed]
====Carbonfibre Wrapped====
{{Infobox_Exhaust |
|
| Material = Carbonfibre wrapped silencer
| Weight = 10kgs
| dB =
| Price =
| Suppliers =
| Web =
| Notes = Cat Back
}}

===Blueflame===
Official website - [http://www.blueflameperformance.com/contact.asp Blueflame]
====Titanium====
{{Infobox_Exhaust |
| image = 340rtitanium.jpg
| Material = Titanium
| Weight = 5.4Kgs
| dB =
| Price =
| Suppliers =
| Web =
| Notes = Cat Back
}}

===KOMO TEC===
Official website - [http://www.komo-tec.com/index.php KOMO TEC]
====Sportauspuff Edelstahl Komo-Sport 340R====
{{Infobox_Exhaust |
| image = 369_0.jpg
| Material =
| Weight =
| dB =
| Price = 899 EUR
| Suppliers = KOMO TEC
| Web = [http://www.komo-tec.com/product_info.php/products_id/369 Click Here]
| Notes = Cat Back
}}

[[Category:Exhaust]]
[[Category:Lotus Elise]]
[[Category:S1]]

Geo Setups

2025-08-15T20:41:16Z

Lithopsian: /* Geo setting X does Y */ caps

== Standard Setups ==

===Elise/Exige===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe [Degrees] || Camber || Toe [Degrees]
|-
| Standard S1 || 140/140mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| Standard S2 || 130/130mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| S2 135R || 120/120mm || +3.7° || 0° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 340R Road || 100/110mm || +3.8° || -0.5° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.5mm IN each side [0.20°]
|-
| 340R Track || 100/110mm || +3.8° || -1.8° || 0.5mm OUT Overall [-0.07°]|| -2.7° || 2.5mm IN each side [0.33°]
|-
| Exige S1 || 112/122mm || +3.8° || -0.5° || 0.1mm OUT Overall [-0.01°]|| -2.4° || 1.2mm IN each side [0.16°]
|-
| Exige S2 || 130/130mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige 240R || 120/120mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige V6 Cup || 130/136mm || +2.8° || -0.4° || 0.4mm OUT Overall mm [-0.06°] || -1.9° || 2.5mm IN each side [0.30°]
|-
| Exige 380/410/430 Cup || 130/136mm || +2.8° || -0.8° || x.xmm OUT Overall mm [-0.12°] || -2.10° || x,xmm IN each side [0.6°]
|-
| 111R || 130/130mm || +3.8° || -0.1° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 211 || 100/110mm || +4.0° || -1.4° || 0mm [0.00°] || -2.5° || 1.2mm IN each side [0.16°]
|-
| Msport || 100/110mm || +3.8° || -0.3° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.2mm IN each side [0.16°]
|-style="background-color:#fed200;"
| colspan=7 | Non-Standard Geo Settings
|-
| a forum hero S2 race || 110/115mm || +3.6° || -2.0° || 0.5 mm OUT each side [-0.07°] || -3.0° || 1 mm IN each side [0.13°]
|}

The standard settings are used when car is loaded with 2x75kg passengers and half tank of fuel.

===Evora===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe || Camber || Toe
|-
| Standard || 125/147mm || +5.2° || -0.3° || 0mm || -1.6° || 1.5mm IN each side
|-
|}

Converting toe from mm to degrees:

# Measure the rim diameter in mm as the size e.g. 17" is not the actual diameter your measurements are based on.
# Multiply the result by PI to get the circumference.
# Divide the result by 360 to get mm per degree.
# Divide the toe mm by the mm/degree result to get toe in decimal degrees

Or Excel =DEGREES( ASIN( TOE_IN_MM / ( RIM_DIA_INCHES * 25.4 )))

Or use the calculator on this page, hypotenuse is the rim diameter the toe per wheel (total toe divided by 2) in mm is width (or toe in degrees is angle A). * http://joyfulcoder.net/sohcahtoa/

== Geo setting X does Y ==
Some starter guidelines although its really really complex stuff and dependent on many other factors;

* Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the understeer, although the inside edges of the tyres will wear slightly faster. Increasing past -1.0° is great for high speed corners but can compromise low speed cornering, will reduce braking effectiveness and it will tramline on the road.

* Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer with front camber. Look at the ratios on the standard settings and maintain the front/rear % delta.

* Front toe affects stability or responsiveness of turn in. Front Toe out (standard) makes the car more responsive turn in but causes additional drag in straights. Front toe in is more stable in straight line.

* Rear Toe controls the stability of the rear through the corner. Rear toe in (standard) makes the car more stable and apparently the Elise toes in more at the rear as the suspension compresses. Rear toe out causes the rear to steer out from the corner, reducing stability.

== Factors affecting Geo ==
When asking questions on the forums about "the best geo for ..." the following need to be considered so make an effort to specify;

* What you are using the car for (road, sprint race, endurance race)
* Tyre spec (section & compound)
* Spring rates
* Damper spec and settings
* Ride height
* Current Geo settings
* Perceived problems with current setup

== Setting your own geo ==
Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings. With a lot of variability in quality at alignment centres (and Lotus dealers !) for the best results put the effort in yourself and build a string based alignment rig which can be more accurate than a computerised laser system. To make a DIY geo/alignment rig see:[[Geo Alignment Rig (Home Made)]]

1. The Hunter computerised laser alignment system is one of the best (the variability is quality of the operator) http://www.alignmycar.co.uk will find a local place with a Hunter alignment system who will provide a setup sheet showing castor, camber and toe (probably in dd:mm:ss rather than decimal degrees) for £15 and can set the front and rear toe for another £30.

2. If you are going to DIY you must have the relevant S1 or S2 service manual suspension sections. Setting castor and camber is straightforward as a caster washer and camber shim have fixed values, whereas toe is delicate - which way do you wind the flats and a quarter turn of the track rod can alter the toe by 2mm (e.g. just tightening the locknuts).

'''Absolutely critical to getting a good geo is having the right ballast in the seats e.g. for a 780Kg race Elise the difference between empty and an 85Kg driver is 5mm ride height, 0.2° camber and 1mm toe. (Depending on Spring rates used) Don't let your alignment place guess'''

==See Also==
* http://arc.seloc.org/viewthread.php?tid=52913 - The pole & string thread by Randy
* http://arc.seloc.org/viewthread.php?tid=49382
* http://arc.seloc.org/viewthread.php?tid=106461
* http://forums.pelicanparts.com/porsche-911-technical-forum/581498-stringless-wheel-alignment-diyers.html

[[Category:Suspension]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]
[[Category:Lotus 2-Eleven]]
[[Category:S2 Exige]]
[[Category:Lotus Europa]]
[[Category:Lotus Evora]]
[[Category:VX220]]

Geo Setups

2025-08-15T20:40:51Z

Lithopsian: /* Factors affecting Geo */ sp

== Standard Setups ==

===Elise/Exige===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe [Degrees] || Camber || Toe [Degrees]
|-
| Standard S1 || 140/140mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| Standard S2 || 130/130mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| S2 135R || 120/120mm || +3.7° || 0° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 340R Road || 100/110mm || +3.8° || -0.5° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.5mm IN each side [0.20°]
|-
| 340R Track || 100/110mm || +3.8° || -1.8° || 0.5mm OUT Overall [-0.07°]|| -2.7° || 2.5mm IN each side [0.33°]
|-
| Exige S1 || 112/122mm || +3.8° || -0.5° || 0.1mm OUT Overall [-0.01°]|| -2.4° || 1.2mm IN each side [0.16°]
|-
| Exige S2 || 130/130mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige 240R || 120/120mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige V6 Cup || 130/136mm || +2.8° || -0.4° || 0.4mm OUT Overall mm [-0.06°] || -1.9° || 2.5mm IN each side [0.30°]
|-
| Exige 380/410/430 Cup || 130/136mm || +2.8° || -0.8° || x.xmm OUT Overall mm [-0.12°] || -2.10° || x,xmm IN each side [0.6°]
|-
| 111R || 130/130mm || +3.8° || -0.1° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 211 || 100/110mm || +4.0° || -1.4° || 0mm [0.00°] || -2.5° || 1.2mm IN each side [0.16°]
|-
| Msport || 100/110mm || +3.8° || -0.3° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.2mm IN each side [0.16°]
|-style="background-color:#fed200;"
| colspan=7 | Non-Standard Geo Settings
|-
| a forum hero S2 race || 110/115mm || +3.6° || -2.0° || 0.5 mm OUT each side [-0.07°] || -3.0° || 1 mm IN each side [0.13°]
|}

The standard settings are used when car is loaded with 2x75kg passengers and half tank of fuel.

===Evora===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe || Camber || Toe
|-
| Standard || 125/147mm || +5.2° || -0.3° || 0mm || -1.6° || 1.5mm IN each side
|-
|}

Converting toe from mm to degrees:

# Measure the rim diameter in mm as the size e.g. 17" is not the actual diameter your measurements are based on.
# Multiply the result by PI to get the circumference.
# Divide the result by 360 to get mm per degree.
# Divide the toe mm by the mm/degree result to get toe in decimal degrees

Or Excel =DEGREES( ASIN( TOE_IN_MM / ( RIM_DIA_INCHES * 25.4 )))

Or use the calculator on this page, hypotenuse is the rim diameter the toe per wheel (total toe divided by 2) in mm is width (or toe in degrees is angle A). * http://joyfulcoder.net/sohcahtoa/

== Geo setting X does Y ==
Some starter guidelines although its really really complex stuff and dependent on many other factors;

* Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the understeer, although the inside edges of the tyres will wear slightly faster. Increasing past -1.0° is great for high speed corners but can compromise low speed cornering, will reduce braking effectiveness and it will tramline on the road.

* Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer with front camber. Look at the ratios on the standard settings and maintain the front/rear % delta.

* Front toe affects stability or responsiveness of turn in. Front Toe out (standard) makes the car more responsive turn in but causes additional drag in straights. Front toe in is more stable in straight line.

* Rear Toe controls the stability of the rear through the corner. Rear toe in (standard) makes the car more stable and apparently the elise toes in more at the rear as the suspension compresses. Rear toe out causes the rear to steer out from the corner, reducing stability.

== Factors affecting Geo ==
When asking questions on the forums about "the best geo for ..." the following need to be considered so make an effort to specify;

* What you are using the car for (road, sprint race, endurance race)
* Tyre spec (section & compound)
* Spring rates
* Damper spec and settings
* Ride height
* Current Geo settings
* Perceived problems with current setup

== Setting your own geo ==
Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings. With a lot of variability in quality at alignment centres (and Lotus dealers !) for the best results put the effort in yourself and build a string based alignment rig which can be more accurate than a computerised laser system. To make a DIY geo/alignment rig see:[[Geo Alignment Rig (Home Made)]]

1. The Hunter computerised laser alignment system is one of the best (the variability is quality of the operator) http://www.alignmycar.co.uk will find a local place with a Hunter alignment system who will provide a setup sheet showing castor, camber and toe (probably in dd:mm:ss rather than decimal degrees) for £15 and can set the front and rear toe for another £30.

2. If you are going to DIY you must have the relevant S1 or S2 service manual suspension sections. Setting castor and camber is straightforward as a caster washer and camber shim have fixed values, whereas toe is delicate - which way do you wind the flats and a quarter turn of the track rod can alter the toe by 2mm (e.g. just tightening the locknuts).

'''Absolutely critical to getting a good geo is having the right ballast in the seats e.g. for a 780Kg race Elise the difference between empty and an 85Kg driver is 5mm ride height, 0.2° camber and 1mm toe. (Depending on Spring rates used) Don't let your alignment place guess'''

==See Also==
* http://arc.seloc.org/viewthread.php?tid=52913 - The pole & string thread by Randy
* http://arc.seloc.org/viewthread.php?tid=49382
* http://arc.seloc.org/viewthread.php?tid=106461
* http://forums.pelicanparts.com/porsche-911-technical-forum/581498-stringless-wheel-alignment-diyers.html

[[Category:Suspension]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]
[[Category:Lotus 2-Eleven]]
[[Category:S2 Exige]]
[[Category:Lotus Europa]]
[[Category:Lotus Evora]]
[[Category:VX220]]

Geo Setups

2025-08-15T20:40:41Z

Lithopsian: /* Setting your own geo */ sp

== Standard Setups ==

===Elise/Exige===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe [Degrees] || Camber || Toe [Degrees]
|-
| Standard S1 || 140/140mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| Standard S2 || 130/130mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| S2 135R || 120/120mm || +3.7° || 0° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 340R Road || 100/110mm || +3.8° || -0.5° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.5mm IN each side [0.20°]
|-
| 340R Track || 100/110mm || +3.8° || -1.8° || 0.5mm OUT Overall [-0.07°]|| -2.7° || 2.5mm IN each side [0.33°]
|-
| Exige S1 || 112/122mm || +3.8° || -0.5° || 0.1mm OUT Overall [-0.01°]|| -2.4° || 1.2mm IN each side [0.16°]
|-
| Exige S2 || 130/130mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige 240R || 120/120mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige V6 Cup || 130/136mm || +2.8° || -0.4° || 0.4mm OUT Overall mm [-0.06°] || -1.9° || 2.5mm IN each side [0.30°]
|-
| Exige 380/410/430 Cup || 130/136mm || +2.8° || -0.8° || x.xmm OUT Overall mm [-0.12°] || -2.10° || x,xmm IN each side [0.6°]
|-
| 111R || 130/130mm || +3.8° || -0.1° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 211 || 100/110mm || +4.0° || -1.4° || 0mm [0.00°] || -2.5° || 1.2mm IN each side [0.16°]
|-
| Msport || 100/110mm || +3.8° || -0.3° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.2mm IN each side [0.16°]
|-style="background-color:#fed200;"
| colspan=7 | Non-Standard Geo Settings
|-
| a forum hero S2 race || 110/115mm || +3.6° || -2.0° || 0.5 mm OUT each side [-0.07°] || -3.0° || 1 mm IN each side [0.13°]
|}

The standard settings are used when car is loaded with 2x75kg passengers and half tank of fuel.

===Evora===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe || Camber || Toe
|-
| Standard || 125/147mm || +5.2° || -0.3° || 0mm || -1.6° || 1.5mm IN each side
|-
|}

Converting toe from mm to degrees:

# Measure the rim diameter in mm as the size e.g. 17" is not the actual diameter your measurements are based on.
# Multiply the result by PI to get the circumference.
# Divide the result by 360 to get mm per degree.
# Divide the toe mm by the mm/degree result to get toe in decimal degrees

Or Excel =DEGREES( ASIN( TOE_IN_MM / ( RIM_DIA_INCHES * 25.4 )))

Or use the calculator on this page, hypotenuse is the rim diameter the toe per wheel (total toe divided by 2) in mm is width (or toe in degrees is angle A). * http://joyfulcoder.net/sohcahtoa/

== Geo setting X does Y ==
Some starter guidelines although its really really complex stuff and dependent on many other factors;

* Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the understeer, although the inside edges of the tyres will wear slightly faster. Increasing past -1.0° is great for high speed corners but can compromise low speed cornering, will reduce braking effectiveness and it will tramline on the road.

* Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer with front camber. Look at the ratios on the standard settings and maintain the front/rear % delta.

* Front toe affects stability or responsiveness of turn in. Front Toe out (standard) makes the car more responsive turn in but causes additional drag in straights. Front toe in is more stable in straight line.

* Rear Toe controls the stability of the rear through the corner. Rear toe in (standard) makes the car more stable and apparently the elise toes in more at the rear as the suspension compresses. Rear toe out causes the rear to steer out from the corner, reducing stability.

== Factors affecting Geo ==
When asking questions on the forums about "the best geo for ..." the following need to be considred so make an effort to specify;

* What you are using the car for (road, sprint race, endurance race)
* Tyre spec (section & compound)
* Spring rates
* Damper spec and settings
* Ride height
* Current Geo settings
* Perceived problems with current setup

== Setting your own geo ==
Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings. With a lot of variability in quality at alignment centres (and Lotus dealers !) for the best results put the effort in yourself and build a string based alignment rig which can be more accurate than a computerised laser system. To make a DIY geo/alignment rig see:[[Geo Alignment Rig (Home Made)]]

1. The Hunter computerised laser alignment system is one of the best (the variability is quality of the operator) http://www.alignmycar.co.uk will find a local place with a Hunter alignment system who will provide a setup sheet showing castor, camber and toe (probably in dd:mm:ss rather than decimal degrees) for £15 and can set the front and rear toe for another £30.

2. If you are going to DIY you must have the relevant S1 or S2 service manual suspension sections. Setting castor and camber is straightforward as a caster washer and camber shim have fixed values, whereas toe is delicate - which way do you wind the flats and a quarter turn of the track rod can alter the toe by 2mm (e.g. just tightening the locknuts).

'''Absolutely critical to getting a good geo is having the right ballast in the seats e.g. for a 780Kg race Elise the difference between empty and an 85Kg driver is 5mm ride height, 0.2° camber and 1mm toe. (Depending on Spring rates used) Don't let your alignment place guess'''

==See Also==
* http://arc.seloc.org/viewthread.php?tid=52913 - The pole & string thread by Randy
* http://arc.seloc.org/viewthread.php?tid=49382
* http://arc.seloc.org/viewthread.php?tid=106461
* http://forums.pelicanparts.com/porsche-911-technical-forum/581498-stringless-wheel-alignment-diyers.html

[[Category:Suspension]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]
[[Category:Lotus 2-Eleven]]
[[Category:S2 Exige]]
[[Category:Lotus Europa]]
[[Category:Lotus Evora]]
[[Category:VX220]]

Bleed the brakes

2025-08-12T18:23:16Z

Lithopsian: move lead image to the right

[[Image:Brake_bleeder.jpg|thumb|Brake bleeder with reservoir]]
If air gets trapped inside the [[brake hoses]] a softer brake pedal is felt. The [[brakes]] need to be bled and the air removed from the system. This procedure is relatively simple, being made much easier with a specialist bleeder.

If you have air in the system (eg. when changing brake hoses) then you'll pretty much always need to mess around with the front callipers to get it all out as the design of them traps the air in the inner piston.

If it's just for flushing the system with new fluid (no air in the system) then it's pretty straightforward and you don't have to mess about with the callipers.

It helps a lot if you have spanners with a 'bend' at the end, like an open ring-spanner to keep the brake hose itself in place as you tighten the connector on the car side using a normal, but thin spanner.

On my (early) S2 there was enough space. On a VX220 I needed to dremel the hole above the connector a little to get enough clearance.

== Procedure ==
=== Flushing system ===

If no bubbles are in the system and you just want to refresh the brake fluid, you can either connect a pressure bleeder or bleed manually.

Order; OSR, NSR, OSF, NSF. Wheels off for the rears, but can do it through the spokes at the front.

''Tip: Offside is Drivers, Nearside is passenger.''

Manually: For each calliper in turn, pump the brake pedal until it is solid then maintain the pressure whilst the other person puts a non-return valve on the brake nipple and releases it (11 mm spanner) until the pedal hits the deck.

Pressure bleeder: Fill bleeder with brake fluid, connect to reservoir, pressurise bleeder. One by one open bleed valves on calipers until fluid runs clear.

=== Changing brake hoses ===
When changing brake hoses or if you have air in the system a possible approach that can save loads of time or troubleshooting when bleeding is this:

- Before changing the hoses, remove the brake pads and fit very worn/old pads (or some strips of steel or wood) in their place

- Press the brake pedal a few times to extend the brake pistons in the calipers (the old pads or wedge are there to keep them from popping out completely!)

- Now disconnect an old brake hose from the car

- Disconnect the old hose from the calliper

- Connect the new hose to the calliper and tighten up

- Have a helper keep the open hose end up as high as possible

- Gently push back the piston in the calliper (hand/finger pressure for the fronts, screw back the rear) until brake fluid just comes out the open hose end

- Now connect the hose to the fixed line on the car and tighten connection

=== Bleeding rear callipers ===

For the rear callipers the rest of the procedure is:

- Pressurise bleeder

- Tap on the new brake hose and calliper with a plastic/wood hammer to dislodge trapped bubbles

- Open the bleed valve and screw the piston back completely

- Bleed it a little more normally and check if any more air bubbles comes out

Once it's clear, close the bleed valve, refit pads and check pedal hardness after pumping a few times to seat the pads. Should be solid.

=== Bleeding front callipers===
==== S1 and non-ABS S2 ====

For the front brakes there are two ways to get rid of the small amount of air in the hose once it is re-connected to the car.

On an S1 and older S2 without ABS you can pump the brake pedal until the pistons come out (as if the pads where worn), attention DO NOT push them to much and get them out of the calipers!

Now open the bleeding nipple and compress the pistons with the flexible hose first while rotating and gently tapping the caliper in order to guide any air bubbles towards the other piston with the bleeding nipple. Push the piston in completely.

Now push the other piston with the bleeding nipple fully in.
This will force any air bubbles out.

Now put the calipers and pads back in place and bleed once more.

Test for pedal firmness.

If this worked then continue with the next caliper.

==== ABS equipped S2 or spongy pedal ====

On more recent cars with ABS, or if you still can't get a firm pedal after the first try then there's still air in this circuit somewhere and you need to bleed it the traditional way.

The approach here is a bit cumbersome because of the design of the callipers that trap air in the inner piston.

If this is the case then the approach is as follows:

- Pressurise the brake bleeder with a low (8 psi) pressure to stop fluid and air traveling upwards to the master cylinder

- Tap on the calliper and hose gently with a plastic hammer to dislodge any bubbles that adhere to the surface

- Remove a front calliper from the upright (2 allen head bolts), invert it so the connectng pipe is at the top and open the bleed nipple

- Tap the brake hoses gently and also tap on the inside of the calliper.

- Then (with your hands) squeeze the INNER piston in. This will empty the inner piston and force the bubbles to the front one. Make sure you push it completely in.

- Now carefully rotate the calliper normal side up again so the bleed nipple is at the top. Try to turn it so any bubbles in the outer piston will not try to go up the connecting pipe again.

- With the calliper 'right side up', tap the calliper again and squeeze the OUTER piston back into the calliper and watch for air bubbles escaping

- Close nipple

- Lightly bolt calliper back onto upright

- Refit pads

- Test for firm pedal after some pedal pumping to seat the pads

- If succesful then tighten calliper bolts

=== Conclusion ===

Using this method to fit new brake hoses and bleed the system the advantages are:

- You only introduce a tiny amount of air in the system, so less to get out again.

- You immediately know if you have air left in this specific part of the circuit if the brake pedal was hard beforehand, but now remains 'soft'. (no long 'hunt the problem' sessions)

== Bleeders ==

Bleed nipples Elise (Brembo) M10 X 1.0 X 30mm

=== Power bleeders ===
safety goggles recommended
Pump up to 10psi, or 20psi...
Fitted with Ø42mm cap and suitable for most European models

=== Eezi Bleed kit ===
Uses the air pressure from your tyre to force the brake fluid through.

Oh, and don't make the schoolboy error I made, when you decide that you've got all the air out then just do a one more cheeky bleed without realising that the reservoir is almost empty. Oh how you'll laugh as you shoot big globs of air into the system... :wall

=== Make your own with plant sprayers ===
* http://www.bmw-m.net/TechProc/bleeder.htm

use it at your own risk, but I made my own Easybleed using one of those spray can with pump included used to spray indoor plants.
worked a treat (as long as there was fluid inside)

* [http://www.blunt.co.uk/hydroponics-shop-uk/hydroponics-products/sprayer-pump-action.jpg Sprayer pump action]

== External links ==
* http://www.elisenet.plus.com/BrakeHoses.htm
* [http://www.motiveproducts.com/ Motive Products - #1 Selling DIY Brake Bleeder]
* [http://www.tool-supplies.co.uk/advanced_search_result.php?keywords=bleeder&search_in_description=1&x=0&y=0 Tool-Supplies.co.uk search results brake bleeders]

[[Category:Brakes]]
[[Category:DIY]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]
[[Category:VX220]]

Geo Setups

2025-07-28T15:06:39Z

Lithopsian: /* Elise/Exige */ split standard S1 and S2 since the ride heights are different (Toyota S2 has a slightly different geo)

== Standard Setups ==

===Elise/Exige===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe [Degrees] || Camber || Toe [Degrees]
|-
| Standard S1 || 140/140mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| Standard S2 || 130/130mm || +3.8° || -0.1° || 0.2mm OUT Overall [-0.03°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| S2 135R || 120/120mm || +3.7° || 0° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 340R Road || 100/110mm || +3.8° || -0.5° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.5mm IN each side [0.20°]
|-
| 340R Track || 100/110mm || +3.8° || -1.8° || 0.5mm OUT Overall [-0.07°]|| -2.7° || 2.5mm IN each side [0.33°]
|-
| Exige S1 || 112/122mm || +3.8° || -0.5° || 0.1mm OUT Overall [-0.01°]|| -2.4° || 1.2mm IN each side [0.16°]
|-
| Exige S2 || 130/130mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige 240R || 120/120mm || +3.8° || -0.3° || 0mm [0.00°] || -1.8° || 1.5mm IN each side [0.20°]
|-
| Exige V6 Cup || 130/136mm || +2.8° || -0.4° || 0.4mm OUT Overall mm [-0.06°] || -1.9° || 2.5mm IN each side [0.30°]
|-
| Exige 380/410/430 Cup || 130/136mm || +2.8° || -0.8° || x.xmm OUT Overall mm [-0.12°] || -2.10° || x,xmm IN each side [0.6°]
|-
| 111R || 130/130mm || +3.8° || -0.1° || 0mm [0.00°] || -1.8° || 1.2mm IN each side [0.16°]
|-
| 211 || 100/110mm || +4.0° || -1.4° || 0mm [0.00°] || -2.5° || 1.2mm IN each side [0.16°]
|-
| Msport || 100/110mm || +3.8° || -0.3° || 0.2mm OUT Overall [-0.03°] || -2.0° || 1.2mm IN each side [0.16°]
|-style="background-color:#fed200;"
| colspan=7 | Non-Standard Geo Settings
|-
| a forum hero S2 race || 110/115mm || +3.6° || -2.0° || 0.5 mm OUT each side [-0.07°] || -3.0° || 1 mm IN each side [0.13°]
|}

The standard settings are used when car is loaded with 2x75kg passengers and half tank of fuel.

===Evora===

{| border=1 cellpadding=5 align=center
|- style="background-color:#fed200; face:bold;"
| rowspan=2 | Geometry || rowspan=2 | Ride Height Front/Rear || colspan=3 align=center | Front || colspan=2 align=center | Rear
|- style="background-color:#fed200;"
| Castor || Camber || Toe || Camber || Toe
|-
| Standard || 125/147mm || +5.2° || -0.3° || 0mm || -1.6° || 1.5mm IN each side
|-
|}

Converting toe from mm to degrees:

# Measure the rim diameter in mm as the size e.g. 17" is not the actual diameter your measurements are based on.
# Multiply the result by PI to get the circumference.
# Divide the result by 360 to get mm per degree.
# Divide the toe mm by the mm/degree result to get toe in decimal degrees

Or Excel =DEGREES( ASIN( TOE_IN_MM / ( RIM_DIA_INCHES * 25.4 )))

Or use the calculator on this page, hypotenuse is the rim diameter the toe per wheel (total toe divided by 2) in mm is width (or toe in degrees is angle A). * http://joyfulcoder.net/sohcahtoa/

== Geo setting X does Y ==
Some starter guidelines although its really really complex stuff and dependent on many other factors;

* Increasing front camber from the default -0.1° to -0.5° each side will dramatically improve the understeer, although the inside edges of the tyres will wear slightly faster. Increasing past -1.0° is great for high speed corners but can compromise low speed cornering, will reduce braking effectiveness and it will tramline on the road.

* Increasing rear camber from the default -1.8° to -2.0° (or higher) makes the car more neutral after you've removed the under steer with front camber. Look at the ratios on the standard settings and maintain the front/rear % delta.

* Front toe affects stability or responsiveness of turn in. Front Toe out (standard) makes the car more responsive turn in but causes additional drag in straights. Front toe in is more stable in straight line.

* Rear Toe controls the stability of the rear through the corner. Rear toe in (standard) makes the car more stable and apparently the elise toes in more at the rear as the suspension compresses. Rear toe out causes the rear to steer out from the corner, reducing stability.

== Factors affecting Geo ==
When asking questions on the forums about "the best geo for ..." the following need to be considred so make an effort to specify;

* What you are using the car for (road, sprint race, endurance race)
* Tyre spec (section & compound)
* Spring rates
* Damper spec and settings
* Ride height
* Current Geo settings
* Perceived problems with current setup

== Setting your own geo ==
Whilst a race prep specialist can charge £200 for a Geo you can DIY castor, camber and toe settings. With a lot of variability in quality at alignment centres (and Lotus dealers !) for the best results put the effort in yourself and build a string based alignment rig which can be more accurate than a computerised laser system. To make a DIY geo/alignmnet rig see:[[Geo Alignment Rig (Home Made)]]

1. The Hunter computerised laser alignment system is one of the best (the variabiltiy is quality of the operator) http://www.alignmycar.co.uk will find a local place with a Hunter alignment system who will provide a setup sheet showing castor, camber and toe (probably in dd:mm:ss rather than decimal degrees) for £15 and can set the front and rear toe for another £30.

2. If you are going to DIY you must have the relevant S1 or S2 service manual suspension sections. Setting castor and camber is straightforward as a caster washer and camber shim have fixed values, whereas toe is delicate - which way do you wind the flats and a quarter turn of the track rod can alter the toe by 2mm (e.g. just tightening the locknuts).

'''Absolutley critical to getting a good geo is having the right ballast in the seats e.g. for a 780Kg race Elise the difference between empty and an 85Kg driver is 5mm ride height, 0.2° camber and 1mm toe. (Depending on Spring rates used) Don't let your alignment place guess'''

==See Also==
* http://arc.seloc.org/viewthread.php?tid=52913 - The pole & string thread by Randy
* http://arc.seloc.org/viewthread.php?tid=49382
* http://arc.seloc.org/viewthread.php?tid=106461
* http://forums.pelicanparts.com/porsche-911-technical-forum/581498-stringless-wheel-alignment-diyers.html

[[Category:Suspension]]
[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]
[[Category:Lotus 2-Eleven]]
[[Category:S2 Exige]]
[[Category:Lotus Europa]]
[[Category:Lotus Evora]]
[[Category:VX220]]

Vehicle security system

2025-05-14T19:14:35Z

Lithopsian: /* Elise S2 After March 02 */ that would be much more understandable as a new paragraph

==Vehicle Security System==

Various security alarm systems have been used on the Elise, but whichever system is fitted,it is most important that the vehicle owner keeps secure records of the transmitter codes and mechanical key codes to allow replacements to be ordered in case of transmitter or key loss.
New cars are provided with duplicate keys/transmitters, and the security codes are supplied on tabs, stickers or printed cards, which information should be recorded and kept safely with the vehicle documents.

Spare transmitters and keys should be accessible at all times if the grief and misery of lock outs is to be avoided.

Spare or replacement transmitters and keys may be ordered from Lotus dealers quoting thesecurity codes, and are normally obtainable within a few days.
If the security codes have been lost, it is possible for the dealer, having adequately established proof of ownership, to request from Lotus a factory record archive search, for which a small charge is made.
This would of course be of no value if the alarm system or lock set has been replaced since factory build.

===Elise S1 1996 to 2000===

S1 1996 to 2000 model year Elise is fitted as standard with a Lucas 5AS security module which is electronically matched to the engine management system and provides the following security features:

The trapezoidal transmitter fob has two buttons, one smooth and one embossed with a padlock symbol. Replacement transmitters are purchased uncoded, and are matched to the car by a Lotus dealer using a scanner tool.

===Elise Alarm Upgrage Option pre Oct 97===

Optional upgrade on S1 Elise prior to October 1997 was a Cobra Goldline 6019HF,
which meets Thatcham Category One requirements and includes the following features:
- Ingress protection using sensing switches on the front bonnet, engine lid and both
doors;

- Switchable intrusion sensing using a microwave sensor;

- Self powered siren;

- Passive engine immobilisation;

- Dynamic coding of the transmitter key.

When the alarm is fully armed, triggering will occur if:

- a door, bonnet or engine lid is opened;

- movement within the passenger compartment is detected.

- the vehicle power supply is interrupted.

When triggered, the self powered siren will sound and the hazard warning lamps will flash.
The rectangular transmitter fob has a red and a blue button. Replacement transmitters are
ordered quoting the security code.

===Elise Alarm Upgrage Option After Oct 97===

Optional upgrade on S1 Elise prior from October 1997 was a Cobra 6422, which
meets Thatcham Category One requirements and includes similar features to the 6019HF.
The round shape transmitter fobs have a large and a small button. Replacement
transmitters are purchased uncoded, and are programmed to the car by the owner using the
security touch key.

What the manual doesn't mention is that if your fob doesn't work (after changing the battery for example), you don't necessarily have to go through that whole procedure. The S1 manual doesn't tell you this, but the simple sequence to resync the fob is as follows:

1) Remove battery & wait 10 seconds before re-installing (re-sync can fail if this step is missed)
2) Hold down both buttons (remote fob LED will light), holding down for approx.10 seconds until LED turns off.
3) Release both buttons.
4) Press large button for one second, LED will flash…re-sync complete

I did this with two separate fobs last weekend and it worked a treat.

NeilGC

===340R Exige S1 and Elise S2 Before Feb 02===

S2 Elise prior to Feb. '02 and all 340R and S1 Exige models, use a Meta vehicle
security system, being either an M36 T2 electronic immobiliser meeting Thatcham category
2 requirements, or, as an optional upgrade, a full M99 T2 alarm system incorporating M23
cockpit intrusion sensing and a self powered siren, which meets Thatcham 1

The optional upgrade includes the following security features:

- Ingress protection using sensing switches on the front access panels and engine lid.
- Selectable cockpit intrusion sensing using a microwave sensor.

- Automatic (passive) engine immobilisation to prevent the engine from being started.

- Self powered siren to maintain protection if the vehicle battery is disconnected.

- 'Dynamic coding' of the transmitter keys;
Each time the transmitters are used, the
operating frequency is randomly changed to guard against the possibility of code copying.
The alarm will be triggered by any of the following actions:
- Opening a door, engine lid or front access panel;
- Movement detected within the cockpit;
- Energising the ignition circuit ('hot wiring');
- Interruption of the vehicle battery power supply.
The transmitter fob with single button is incorporated into the head of the mechanical door key.
Replacement transmitter/keys may be ordered either uncoded (if only a mechanical blade is required, into the head of which the original transmitter board may be transferred), or coded (if security code is supplied). New coded transmitters must then be programmed to the car by the owner using a button press sequence.

=== Elise S1 Cobra ====

If you have no touch key and change the battery in the Fob use the procedure on the Youtube video, it works:

https://www.youtube.com/watch?v=obFco5z3OA8

===Elise S2 After March 02===

Elise models built from approx. March '02, are fitted with a Cobra 8185 engine electronic
immobiliser meeting Thatcham category 2 requirements, but for enhanced theft and vandal
protection, the car can be specified with a Thatcham 1 category Cobra 8186 upgraded alarm
which includes cockpit intrusion sensing and a self powered siren.

Online User guide http://auto.manualsonline.com/manuals/mfg/cobra_electronics/8186.html

Immobiliser (8185 & 8186): In order to provide a measure of automatic vehicle security,
independent of any driver initiative, both 8185 and 8186 systems will ‘passively’ immobilise
the engine’s cranking and running circuits after the first occurring of the following
approximate time delays:

i) Four minutes after switching off the ignition.

ii) One minute after switching off the ignition and opening either door.

8186 Alarm System: As an optional upgrade, the Elise may be specified factory built with a Cobra 8186 vehicle security system which incorporates the following features:

- Ingress protection using sensing switches on both doors, both front body access panels, and the engine cover.

- Selectable cockpit intrusion sensing using a microwave sensor.

- Automatic (passive) engine immobilisation to prevent the engine from being started.

- Self powered siren to maintain protection if the vehicle battery is disconnected.

- 'Dynamic coding' of the transmitter keys; Each time the transmitters are used, the operating frequency is randomly changed to guard against the possibility of code copying.

- Personal protection by remote activation of siren.

The alarm will be triggered by any of the following actions:

- Opening a door, engine lid or front access panel;

- Movement detected within the cockpit;

- Energising the ignition circuit ('hot wiring');

- Interruption of the vehicle battery power supply.

The transmitter fobs are the same as used on Cobra 6422 (see above).
Replacement transmitters are purchased un-coded, and are programmed to the car by the owner using a Personal Identification Number (PIN) supplied with the alarm.

===Elise & Exige S2 2008? Onwards===

[[Image:Transmitter_Key.gif|thumb|left]]
These models have a single key fob that combines ignition key and alarm.
They are oval (think like an eye) in shape and have 3 buttons, one round with a Lotus logo and 2 flat black ones.
{{clr}}

====Transmitter Key battery replacement====

The transmitter keys will normally operate within a range of 5 metres from the car, but this may be reduced by the presence of other radio signals in the vicinity. The transmitters are powered by a long life 3v lithium battery (type CR2032) which should last for 3 years. However, it is recommended to renew the batteries every 12 months.

[[Image:Transmitter_Battery_Replacement.gif|thumb|left]]
# Using a small screwdriver, prise open the back panel of the key case using the slot by the keyring hole.
# Remove the old battery and wait for 10 seconds before inserting the new battery with the +ve sign uppermost and holding the battery only by the periphery
# refit the back panel, pressing firmly to engage the clip.
# the transmitter should now operate normally
{{clr}}

====Emergency Disarming/mobilising====

If the transmitter keys are lost or damaged, the alarm system owner's 5-digit PIN may be used to disarm the alarm, PROVIDED that access is available to the cabin:

#turn on the ignition, the alarm tell tale will light
#If the alarm is armed, accessing the cabin or turning on the ignition will trigger the alarm until completion of this emergency process
#Within 10 seconds, turn the ignition off; the tell tale will begin to flash
#After a number of flashes corresponding to the first digit of the PIN, turn on the ignition. Note that the first flash may not be of full duration (but it is still to be counted) dependent on the waveform position at time of ignition switch off
#Turn off the ignition and after a number of flashes corresponding to the second digit of the PIN, turn on the ignition. Repeat this process until all 5 digits have been completed. Note that 10 flashes correspond to a zero digit
#If the PIN is entered correctly, the alarm will sound a short beep and will now be overridden and the engine mobilised. However passive immobilisation will still occur after an ignition off time of 40 seconds, requiring a repeat of the above procedure to mobilise. Passive arming and passive door locking cannot occur until a transmitter is used to operate the alarm.

If at any stage of the process, a number is entered incorrectly, the system will immediately revert to the start, so that the whole PIN must be re-entered.

====Programming Additional Transmitters====

A max of 6 transmitters may be programmed to the car, any thereafter overwriting the first to have been programmed.

#With the engine immobilised (tell tale flashes briefly once per second), turn on the ignition
#Enter the PIN as detailed above, followed by the additional two digits 1, 1.
#The tell tale will flash rapidly for one second, then turn off.
#Within 8 seconds, press any button on the transmitter to be programmed. The tell tale will then pulse rapidly and the siren will beep
#Within 10 seconds, press any button on the next transmitter to be programmed (if applicable) and repeat this process for all remaining transmitters.
#When all transmitters have been programmed, wait for 10 seconds , of turn off the ignition.

To disable a lost or stolen transmitter from the system, use the above procedure to programme 6 transmitters, if necessary, repeatedly reprogramming the same transmitter if less than 6 programmed transmitters are to be used.

pfk manual elise s2 alarm http://www.warp.at/liz/pfk457/D457520RV3.pdf

WORKS ON 2005 CAR

REMOTE KEY FOB - PROGRAMMING - USE WHEN ADDING A NEW REMOTE INTO THE SYSTEM

IGNITION MUST BE ON AND THE ALARM OFF

STEP 1 – PREPARING ALL REMOTE KEY FOBS - ALL FOBS MUST BE DONE SIMULTANEOUSLY

Press and hold both buttons on remote until the LED stops flashing (about 10 seconds).

Do this for all remotes to be programmed

The LED on the remote should stay on until after programming.

If the LED on the remote extinguishes by the time you want to program, the key has gone into battery
saving mode, press large button once to bring the LED back on then proceed with programming.

STEP 2 – ENTER PIN

1) Turn ignition ON and OFF 3 times within 5 seconds.

2) Security LED will blink once indicating that the security code can now be entered.

3) Enter security code as follows:

.... a) Turn ignition ON & count number of blinks representing 1ST digit of code then turn ignition OFF.

.... b) Repeat for 2nd digit.

.... c) Repeat for 3rd digit.

.... d) Repeat for 4th digit.

4) Turn ignition ON and LED will come on permanently if correct code has been entered

STEP 3 – COMPLETE THE REMOTE KEY FOB PROCEDURE

1) Press and hold the large button on one of the remotes until the security LED light in the tachometer goes out then comes back on.

2) Do this for each remaining remote

3) Turn off the ignition and check each remote for the correct operation.

[[Category:Electrical]]
[[Category:Lotus Elise]]
[[Category:Lotus Exige]]
[[Category:S2 Exige]]
[[Category:S1]]
[[Category:S2]]

Cambelt

2023-08-21T19:36:52Z

Lithopsian: /* Cambelt Continued */ [retty sure it is the one of the left

'''PLEASE ADD INFORMATION, WORK IN PROGRESS'''

===Part numbers===

For auto tensioner:

Rover pt no, LHN100560

Gates pt no. 5497XS

Piper pt no TBP33

For manual tensioner:

Rover pt no. LHN100390

Gates pt no. 5416XS

Piper pt no. TBP17 wide

===Changing the Cambelt (Auto Tensioner inc Water Pump)===

It is much easier to change the cambelt with the rear clam off but this is not necessary and access through the drivers rear wheel arch with the liner removed is still excellent compared to most 16v engines.

Instructions are for a "clam on" change

The rear of the car needs to be a high as possible to allow access to loosen and torque up the crank bolt (210Nm is tight)

((CLICK ON IMAGES TO ENLARGE ))

===Tools Required===

You will require a cut down 22mm socket to fit in the limited space between the crank pulley and the chassis (a 6 sided socket is stronger than a 12sided. Silverline do one for a couple of ££'s from Amazon)

[[File:Cambelt2.jpg|thumb|none|Gap]]
[[File:22mm Socket Marked.JPG|thumb|none]]
[[File:Cambelt4.jpg|thumb|none]]

You will also need a

. 1/2" breaker bar to loosen the crank bolt. As long as possible (don't try and use a ratchet handle, you'll break it and get a hernia to boot)

. a torque wrench capable of operating up to 210Nm (with a slim head if possible)

. A Rover K Series camshaft locking tool

===Method===

1. Run the rear of the car up on ramps if you have them and remove the rear undertray and diffuser. Loosen the RHS rear wheel nuts while the weight of the car is still on the wheel

2. Remove the spark plugs (this will allow the engine to be turned over much easier
using the crank bolt as required below

3. Jack up the RHS of car higher still and place axle stands at the B and C positions in the diagram (if you don't have ramps then jack and support with axle stands in stages, as the tilt on the car can easily cause it to slip off a jack on it own)

[[File:Jacking Positions.JPG|thumb|none]].

Try and get the car high enough that you can kneel with your head inside the rear wheel arch (when the liner is out) as this is a comfortable working position allowing you to reach into the engine bay through the arch

4. Move the ramp out of your way and remove RHS rear wheel

5. Remove RHS rear wheel arch liner

6. You may wish to remove the brake disc on the RHS rear wheel to allow greater access into the wheel arch when working (it is not necessary to do this)

[[File:Cambelt1.jpg|thumb|none|View with Liner Out]]

7. Loosen the pivot bolt and clamp bolt on the alternator

8. Loosen the adjuster bolt to move the alternator towards the engine and provide slack on the the belt. The bolt has a fine pitch so expect to turn it many times before the belt slackens (If you intend to refit the existing alternator belt, before undoing the adjuster bolt, mark the position of the clamp bolt on the slotted bracket, so that you know exactly where to tighten the belt up to on reassembly)

[[File:Alternator Diagram.JPG|thumb|none|Alternator bolts]]

9. Remove the alternator belt

10. Unbolt the upper cam belt cover and manoeuvre it upwards and out via the the engine bay (the cover to clam clearance is tight, but it will come out with minimum force if jiggled about a bit)

Ensure that you do not lose the rubber seal that press fits onto the bottom edge of the upper cover

[[File:Cambelt3.jpg|thumb|none|Top Cover Removed]]

11. Before loosening the crank bolt place a suitably sized screwdriver or allen key in the visible flywheel ring gear next to the drivers side driveshaft to prevent the engine rotating (I found an allen key much less likely to slip)

[[File:Allen Key Crank Lock.JPG|thumb|none|Crank Locked with Allen Key]]

12. From under the car and using the breaker bar with the cut down socket, loosen the crank bolt (you are likely to have to brace your knees/feet against the underside to gain enough purchase to undo the bolt. Folk on here have snapped breaker bars doing this, so take care)

13. Remove the crank bolt, the large washer (note orientation) and then the crank pulley

[[File:Crank Pulley and Bolt.JPG|thumb|none]]

14(a). Remove the lower cam cover

14(b). Replace the crank bolt (only) and hand tighten.

15(a). Before removing the cambelt the engine requires to be placed in a known positioned with No1 piston (closest to belt end) at 90deg BTDC. As a visual aid to help find 90 BTDC, place a long screwdriver/large tie wrap/clean garden cane etc etc down through hole where you removed the spark plug on cylinder 1. It will rest on the piston crown and rise and fall with the engine rotation as required in part 16 and indicate piston location and direction. ***Make sure that whatever you use is long enough so that it does not fall into the engine at piston BDC !!! ***

15(b). Its worth highlighting the camshaft sprocket alignment marks, the crankshaft sprocket alignment marks and the engine block alignment mark with some Tippex (or white paint) for ease of viewing

[[File:Cambelt5.jpg|thumb|none|Camshaft Alignment Marks]]

[[File:Cambelt6.jpg|thumb|none|Crankshaft and Block Alignment Marks]]

16. Remove the screwdriver/allen key from the flywheel teeth, and with the car out of gear. Turn the engine using a rachet/spanner on the crank bolt (only ever turn clockwise), until the camshaft and crank shaft alignment mark line up as above AND the visual aid in cylinder 1 shows the piston is half way up the cylinder on the rise. Camshaft sprocket marks should face each other in a line with the centre bolts of each shaft. The crank dimple marks should straddle the block mark.

[[File:K Alignment Marks.JPG|thumb|none|K Series Camshaft Alignment Marks]]

17. Replace the screwdriver or allen key in the flywheel and place the camshaft locking tool into place

[[File:Cambelt7.jpg|thumb|none|Cam Locking Tool]]

18. Mark the old belt/sprockets at both cams and on the crank. When the old belt is off, transfer these marks to the new belt (carefully count the belt teeth). When fitting the new, the marks will ensure it is not out by a tooth anywhere along its length (the K series will run without damage when the belt is out by a tooth either way but not very well!!).

[[File:Cambelt8.jpg|thumb|none|Belt to Sprocket Double Check]]

19. Unbolt the tensioner centre bolt, remove the tensioner and slide off the cambelt.

20. The engine mount prevents the old belt from being removed completely. There are two ways of getting the old belt out and new one in

20a (Thanks to Dave Andrews for this tip):
The easiest method is to remove one bolt on the engine mount at a time and weave the belt in between the bolts. Slacken both so that the engine drops by 12-15mm or so. Remove one bolt and push the belt into the gap between. Replace the bolt and tighten to where it was (I.E. 12mm gap), then remove the other bolt and push the belt the rest of the way through the gap. Reverse the process to get the new belt in, then do up both bolts to the correct torque.

[[File:Engine Mount.JPG|thumb|none|Engine Mount]]

20b The alternative method, is to place a trolley jack under the engine (use a piece of wood between to spread the contact load), jack the engine up slightly and remove the engine mount bolts completely. Takes a bit longer and if the engine moves ever so slightly back or forward it can be a PITA to get the bolts started in the threads again

===Waterpump Change===

21 If you intend to change the waterpump as well (and if you're in here already its probably worth it !!), now is the time to do it. Drain the coolant by undoing and hoses that enter both side rails at the rear of the car

22. Unbolt the old pump and remove it. (Expect more coolant to flow from the engine block). There are 6 bolts circled in the photo. The top left is bolted from the rear side, the bottom right is a pillar bolt (used for the front cover as well) and there are two dowels, squared in the photo. Check that the old rubber sealant ring was removed with the old pump and if there is any corrosion around the face/dowels remove with wet an dry paper. The block surface should be clean to allow the new pump to fit well

[[File:Waterpump Bolts.JPG|thumb|none|Waterpump Bolts and Dowels]]

23. Ensuring the new sealant ring is in place in the groove on the new pump and fit the pump (you can use some (proper) automotive RTV silicon to hold the new sealant ring in place if required). Tighten the bolts in stages alternating between diagonally opposite bolts to 10Nm

===Cambelt Continued===

24. Before fitting the new tensioner, it is advisable to mark the end of the tensioner wire pointer with a drop of Tippex/white paint to alow it to be seen clearer during positioning

[[File:Cambelt10.jpg|thumb|none|New Tensioner on left with Pointer Marked]]

25. Fit the new tensioner into position and secure with the centre bolt but leave it loose enough that the tensioner will wobble quite freely to give some freeplay while fitting the new belt. Ensure that the wire loop on the tensioner is hooked behind the bolt on the block.

The tensioner lever (the part where the allen key fits, should be at the 9 o'clock position)

[[File:Auto Tensioner Wire.JPG|thumb|none|Tensioner Wire Hook Position]]

26. Fit the new belt onto the crank pulley first. If you marked the belt as per section 18 above, line up the mark on the belt with the sprocket mark. Fit the belt so that approx half of the width is on the sprocket/half is hanging off the front edge. Again this gives you more leeway/flex with the belt as you feed it on.

27. Keeping the long RHS of the belt taught, feed it over the RHS (exhaust) cam sprocket then over the LHS (inlet) cam sprocket, again lining up the white marks you placed on it earlier and again only pushing the belt on half way

[[File:Cambelt12.jpg|thumb|none|New Belt - Aligning Crank Sprocket Mark]]

[[File:Cambelt11.jpg|thumb|none|New Belt - Aligning Cam Sprocket Marks]]

28. Feed the belt up around the water pump then around tensioner. Once around all the mounting points you can then push the belt fully onto all the sprockets until seated fully

29. Tighten the tensioner centre bolt, not fully, but enough to pull it against the block

30 From the service manual:-

[[File:Auto Tensioner Setup.JPG|thumb|none|Auto Tensioner Adjustment]]

30a. "Tighten the centre bolt until it is just posible to move the tensioner lever"

30b. "check the belt is central around gears and pulleys

30c. "Using a 6mm Allen Key, rotate tensioner anti-clockwise and align the centre of the indent on the tensioner pointer to the index wire

ENSURE that the pointer approaches the index wire from above. Should pointer go past index wire, release tension completely and repeat tensioning procedure"

30d. "Ensuring that the pointer maintains the correct position, tighten centre bolt to 25Nm"

(It is quite difficult to hold the allen key on the lever and use a torque wrench in this location. If you tighten this bolt up using the "calibrated hand" method, do not overtighten the bolt.

31. Remove the cam locking tool and the crank locking allen key/scredriver and using a ratchet on the crank bolt, rotate the engine 2 turns clockwise. Check the tensioner pointer is still in the correct position

32. Remove the crank bolt, refit the cambelt lower cover.

33. Ensuring the mating surfaces of the crank pulley, washer, bolt and sprocket are clean, refit the crank pulley, washer and bolt. (Do not use a thread lock compound). Make sure the notch on the pulley is keyed to the crank before tightening the bolt hand tight

34. Replace the crank locking allen key/screwdriver and torque the crank pulley to 210Nm. This is a significant force even with a long torque wrench. Do not be tempted to just beef up the bolt with a big spanner, numerous instances of the the crank nose being worn away, the pulley undoing and the crank sprocket sliding off because of a loose bolt have been documented with the K series

35. Remember to remove the crank locking allen key/screwdriver !!!!

36. Refit the alternator belt

37. Refit the upper cam belt cover (be careful that the rubber sealing gasket on the lower edge is in the correct place. Its easily knocked off)

38. If you have changed the water pump, reconnect all coolant hoses and refill the system with new coolant.

39. I always turn the car over on the starter with the spark plugs removed just as a double triple check that all is well. (not advisable on cars with coil packs as they can be damaged. Better to remove the power to the fuel pump) If it doesn't rattle like a bag of nails :-), then refit the spark plugs and leads, start the engine

40. Lower the car and bleed the cooling system per the service manual or

http://wiki.seloc.org/a/Bleed_the_cooling_system

CHOPPER.

===NOTES===

1. Alternative methods used to lock the crank include having the car in gear and an assistant press on the brakes VERY hard. It has worked for some and it appears OK for loosening the crank bolt but when doing up any slipage will throw out the timing !!!

Another method to undo the crank bolt that has been used is jam the socket and breaker bar against the groung/something very rigid, and use the starter motor to turn the engine. The bolt being held will undo as the crank turns. Use this method at your own risk.... and make sure the car is out of gear when you do it

Another method to block the crank bolt when you remove/put the pulley :
[[File:manual.jpg|thumb|left]][[File:IMG_0065 (Personnalisé).JPG|thumb]]

* Make sure the car is out of gear

* Unscrew the starter (bolts n°25 & 27) and take off the rear closure plate (n°26).

* Then you have accesse to the flywheel... Now you need a strong cornered plate that you'll can wedge between the sump and the flywheel. Put it in the red position when you unscrew the pulley (like in the picture), put it in the blue position when you screw back the pulley...

* Just have to put back the starter and the closure plate when you're done.

2. There have been a small number if instances reported where the cambelt centre tensioner bolt has become seized to the block through corrosion/overzealous tightening or the use of thread lock. Before stripping the engine to find this may be the case (and you now have a car that is incapable of being driven to a garage/mechanic), you may wish to check the tensioner bolt will loosen. This is possible by removing the upper cam belt cover before all else and trying to move the bolt a quarter turn. If it moves, tighten it back up and follow the normal procedure above

Useful video:
http://www.mgf.ultimatemg.com/group2/engines/index.htm

Useful link to another guide fitting the manual tensioner
http://www.tadts.com/instructions/engine/100016.html

Quick Guide

Thread here: http://forums.seloc.org/viewthread.php?tid=314945&page=1#pid5349364

===Tensioner===

'''PLEASE ADD INFORMATION'''

Auto or Manual

I looked at the information on Eliseparts to ascertain if our engine was fitted with a manual or auto tensioner.
It sugested auto, i purchased an auto one but it turnd out to be a manual.
be warned, eliseparts will not allow you to return the miss purchased item and they stipulate this on line.

===See Also===

'''PLEASE ADD INFORMATION'''

[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]

Heater Matrix

2023-05-25T12:51:41Z

Lithopsian: new link for EP matrix, although currently out of stock

[[Image:Thermostat closed.JPG|thumb|right|Cooling system showing the location of the matrix just behind the radiator]]

The heater matrix is a small radiator through which the [[coolant]] runs and warms the air which enters the cabin. On the S1, it is located on the driver's side, near the [[battery]]. The heater matrix is mounted vertically to the side of the blower fan unit.

When the matrix fails, coolant leaks out of it's pipes and into the heater system, resulting in a fine mist entering the cabin through the ventilation system and misting up the windscreen. With a badly failed matrix, a micro-climate can form in the passenger footwell with mist rising and falling whilst driving.

A replacement heater matrix can be purchased from [https://www.eliseparts.com/shop/heating-ventilation/s1-elise-exige-heater-matrix-a111p6011f/ EliseParts] (part no AW38506, manufactured by KL Automotive, 01827 300 100).

Alernatively a pattern part for the S1 heater matrix matrix can be obtained from http://www.demisterman.co.uk/ (The matrix also is identical to that used on the TX2 London black cab)

elise-shop.com has developed a [http://www.elise-shop.com/heater-matrix-standard-or-upgraded-elise-exige-p-446.html high capacity heater matrix] which has 30% more capacity, but same shape, yet thicker than the original heater matrix.

== Replacing the heater matrix ==

{{Infobox Timetools|time=4 - 6 hours|tools=Torx T10 screwdriver, socket set, telescopic magnetic device, glue for the plastic matrix cover, new heater matrix}}

[[Image:1999EliseHeaterMatrix.JPG|thumb|left|Photo of an old failing heater matrix from a late 1999 S1 Elise. Note the bending of the matrix elements where the rivets were driven into the side of the plastic case.]]

This is a tricky job due to the location of the matrix and the position of the screws holding it in place.

First, [[Replace the coolant|empty the system of coolant]]. This can be done by first unscrewing the coolant reservoir tank cap, then removing the drivers-side wheelarch liner ([[Remove the wheels|remove the wheel]] first!) and undo the [[radiator]] feed hose. Drain into a bucket and dispose of safely. The radiator hose and wheelarch liner can be refitted as this side of the car doesn't need to be accessed again. Some people have reported successfully replacing the matrix without draining the system of coolant by clamping the feed and return hoses before disconnecting them from the matrix and then filling the new matrix with coolant via a funnel.

Next remove the plastic radiator cowl/surround with a Torx T10 screwdriver and [[Battery#S1_Fitting|remove the battery]].

=== Removing the matrix unit ===

Some vehicles have the matrix/blower assembly held together by an rubber band as shown in the workshop manual. Other vehicles have the two held together by a metal bracket and nut on both the top and bottom. These instructions describe removal of the matrix when the matrix/blower assembly are held together with the metal bracket.

It may be possible to bust the two rivets on one side of the matrix cover to allow the matrix to be removed without unscrewing the matrix/blower assembly. If this is possible, it will significantly reduce the disassembly/assembly time. If not, follow the procedures below:

[[Image:1999EliseMatrixBlowerAssembly.jpg|thumb|right|This model has a single green ceramic terminal block and a metal bracket and nut holding the matrix case to the blower case. Earlier S1 models varied.

You can see a spanner to the left of the green ceramic block removing one of the bolts holding the blower to the chassis. ]]
The matrix/blower assembly is held in place by 4 screws. Remove the metal [http://www.eliseparts.com/products/show/84/166/flexible-heater-ducting/ flexible heater ducting] and the hoses into and out of the matrix itself. One of the screws is just inside the outlet from the blower where the hose attached. Two are into the bulkhead below the radiator behind the cylindrical green ceramic terminal block. And the fourth is closer to the battery again into the bulkhead below the radiator. It's easiest if you remove the green ceramic terminal block - it's simply held on by the metal at each end which can be squeezed together and pulled out of the center of the green cylinder. Early Elise models had 3 cylindrical terminal blocks mounted on the blower. Later models had just one.

The wire which controls the hot/cold flap sits on top of the assembly. It cannot be removed while the cable is held by the spring clip and the flap arm is attached. Either lever off the surprisingly strong sprung metal clip or remove the attachment on top of the flap lever, and then the S-shaped end of the wire can be removed from the control armature. The flap lever is held on with a #10 UNF grub screw (3/32" allen key) and if this is not rusted solid then the arm itself will be corroded on to the flap.

Once the matrix/blower assembly is free, it may still not be possible to get the unit out of the vehicle. The [http://www.eliseparts.com/products/show/61/182/heater-blower-fan/ blower] is connected to the matrix by a metal strip and nut both on the top and the bottom of the assembly. As the matrix/blower assembly is now free and has a certain degree of rotation within the car, the matrix can be separated from the blower by undoing the nut and rotating the metal strip about 30 degrees. The metal strip on the bottom of the assembly is identical. The nuts are prone to rounding or shearing, in which case you will need to drill-out the rivet instead.

With the matrix separated from the blower, you can now remove the matrix from the car. To aid removal, you may need to:

* Rotate the matrix around and extract it upside down
* Remove the front services compartment latch and alarm sensor
* Remove the battery clamp and slide the battery as far out of the way as possible
* Unclip all wiring beside the radiator and pull it on top of the radiator

The matrix unit is held within a plastic case which is riveted and can be glued on the bottom. Take care to remove the rivets without damaging the plastic too much - you only need to remove one pair of rivets as this will allow the plastic to bend enough to remove the matrix.

=== Repainting the metalwork ===

Whilst you have the matrix assembly out you may want to repaint it. The rivets must be drilled out to remove the brackets and blower fan. The parts can then be stripped and repainted. POR15 is recommended for this as Hammerite is rather smelly and will make the hot air supply equally smelly for several months. [[Image:Heater Components.jpeg|thumb|left|Repainted heater matrix parts]]

=== Blower motor ===
The blower motor is manufactured by Gate, part number MP5620/HW1. They are available from Transport Heating Services, OX29 0YG, 01993 849 522, their part number J1512, at approx £100 each (Sept 2012). Stocks are limited as gate has moved its manufacturing to China. (No longer available Feb 2015).

Some people have had success with getting the motor repaired, check the SELOC archives.

A simikar blower motor is fitted to Land Rover's notably the Defender from about 1988 up to roughly 1996. Lot's lying about in scrapyards!

More info on this alternative motor is here:-

http://wiki.seloc.org/a/Heater_Motor,_S1,_Alternative

=== Fan speed control resistors ===

S1 heaters have either one or three large green ceramic resistors which are switched in to regulate the speed of the blower fan. If these are damaged it may be possible to replace them with off-the-shelf electronic parts based on the schematic. [[Image:Heater-resistors-schematic.jpg|thumb|right|Resistor schematic]]

=== Reassembling the matrix unit ===

[[Image:S1BlowerMatrixAssembly.jpg|thumb|left|Photo showing the blower/matrix assembly removed from the vehicle and clamped while being glued. Originally it was held together with rivets and the holes for the rivets can still be seen.]]
Clean out the inside of the plastic case before putting the new matrix inside and either riveting or glueing the case back together.

Take care to orientate the motor so the small hole in its case is facing the ground when it is fitted. Failure to do this will result in your motor filling with water when it rains (don't ask how I know).

Re-assemble matrix/blower unit and then screw it back into the chassis - this may need two pairs of hands and a lot of patience due to the location of the screws. A telescopic magnetic device can be useful to retrieve dropped screws! Re-attach the green cylindrical terminal block, re-fit the hoses into the matrix and replace the battery.

=== Refilling with coolant ===

It may be easier not refitting the plastic radiator cowl just yet as it is easier to get to the radiator bleed screw when bleeding the system. If any of the plastic fasteners were broken whilst removing the radiator cowl, more can be purchased from [http://www.elise-shop.com/index.php?main_page=product_info&products_id=382 Elise Shop].

Finally add coolant back into the header tank and follow the instructions in [[Bleed the cooling system]].

== See also ==
[[Coolant system]]

[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:Engine Cooling]]
[[Category:Fluid]]

Fuel Recycle Canister Solenoid

2023-04-05T16:56:01Z

Lithopsian: say what "it" is, minor grammar and spelling fixes

The function of the charcoal canister is to absorb the hydrocarbons from the fuel tank vent gasses at all times to prevent evaporative emissions losses.

When the engine is running, the canister needs to be purged to prevent it overflowing (breakthrough). Due to control issues, the engine can only accept a certain proportion of it's fuel (HC) as purge hydrocarbons, therefore the purge valve is used to regulate the flow of air/HC out of the can and into the inlet manifold via pulse-width-modulation (PWM) of the valve.

Because the evaporative emissions test has a standard drive cycle as a 'pre-conditioning' drive, the system is designed to purge the canister as quickly and as much as possible after a cold start, to leave it clear for when it gets SHED tested (Sealed Housing for Evaporative emissions Determination - naff US acronym for heating the car up in a sealed box to measure HC emissions evaporated off)

Also, because the ECU has (initially) no clue how much fuel is in the canister, it can only purge when closed-loop lambda (air-fuel ratio) control is operational, which is usually a few tens of seconds after start (at ~20°C)

Unfortunately, the closed-loop lambda control is also used for adapting errors and tolerances of the fuel/air metering system, but this cannot be done simultaneously with purge (due to the unknown amount of purge fuel). Neither can this be done until the oil is at a reasonable temp, since fuel that's diluting the oil will/may begin to boil off and add to the total fuelling via the PCV system (positive crankcase ventilation). Fuelling adaption must be also completed as quickly and effectively as possible during the pre-conditioning cycle to maximise the emissions capability of the car during the 'pukka' emissions test.

So, the plan is this: Nearly as soon as you can run closed-loop (lambda=1) you start purging as much as the engine/control capability will allow. Once the canister purge hydrocarbon flowrate has died down to acceptable levels (or min time period, oil temp), purge is turned off to allow the fuel system errors to be adapted for a while. Purge and fuelling adaption will then operate in turn for the duration of your drive.

...so you might hear your purge ticking coming and going, if it ever was cold enough for you to still hear it.

Systems don't tend to purge at idle for EU-2 cars (or earlier) because it adds complications to idle control. EU-3 cars tend to do so now though, because the new SHED test is 24hours long (up from 2hours? IIRC) The ECU also won't purge when you're off the throttle at higher engine speeds, as all fuelling is turned off in these conditions. That's why you can 'turn the ticking on and off' with the loud pedal.

Fuel Recycle Canister Solenoid

2023-04-05T16:51:48Z

Lithopsian: so great they named it twice

It's function is to absorb the hydrocarbons from the fuel tank vent gasses at all times to prevent 'evaporative emissions losses'

When the engine is running, the thing needs to be purged to prevent it overflowing (breakthrough). Due to control issues, the engine can only accept a certain proportion of it's fuel (HC) as purge hydrocarbons, therefore the purge valve is used to regulate the flow of air/HC out of the can and into the inlet manifold via pulse-width-modulation (PWM) of the valve.

Because the evaporative emissions test has a standard drive cycle as a 'pre-conditioning' drive, the system is designed to purge the canister as quickly and as much as possible after a cold start, to leave it clear for when it gets SHED tested (Sealed Housing for Evaporative emissions Determination - naff US acronym for heating the car up in a sealed box to measure HC emissions evaporated off)

Also, because the ECU has (initally) no clue how much fuel is in the canister, it can only purge when closed-loop lambda (air-fuel ratio) control is operational, which is usually a few tens of seconds after start (at ~20°C)

Unfortunately, the closed-loop lambda control is also used for adapting errors and tolerances of the fuel/air metering system, but this cannot be done simultaneously with purge (due to the unknown amount of purge fuel). Neither can this be done until the oil is at a reasonable temp, since fuel that's diluting the oil will/may begin to boil off and add to the total fuelling via the PCV system (positive crankcase ventilation). Fuelling adaption must be also completed as quickly and effectively as possible during the pre-conditioning cycle to maximise the emissions capability of the car during the 'pukka' emissions test.

So, the plan is this: Nearly as soon as you can run closed-loop (lambda=1) you start purging as much as the engine/control capability will allow. Once the canister purge hydrocarbon flowrate has died down to acceptable levels (or min time period, oil temp), purge is turned off to allow the fuel system errors to be adapted for a while. Purge and fuelling adaption will then operate in turn for the duration of your drive.

...so you might hear your purge ticking coming and going, if it ever was cold enough for you to still hear it.

Systems don't tend to purge at idle for EU-2 cars (or earlier) because it adds complications to idle control. EU-3 cars tend to do so now though, because the new SHED test is 24hours long (up from 2hours? IIRC) The ECU also won't purge when you're off the throttle at higher engine speeds, as all fuelling is turned off in these conditions. That's why you can 'turn the ticking on and off' with the loud pedal.

Cambelt

2023-03-14T17:49:32Z

Lithopsian: /* Waterpump Change */ your -> you're

'''PLEASE ADD INFORMATION, WORK IN PROGRESS'''

===Part numbers===

For auto tensioner:

Rover pt no, LHN100560

Gates pt no. 5497XS

Piper pt no TBP33

For manual tensioner:

Rover pt no. LHN100390

Gates pt no. 5416XS

Piper pt no. TBP17 wide

===Changing the Cambelt (Auto Tensioner inc Water Pump)===

It is much easier to change the cambelt with the rear clam off but this is not necessary and access through the drivers rear wheel arch with the liner removed is still excellent compared to most 16v engines.

Instructions are for a "clam on" change

The rear of the car needs to be a high as possible to allow access to loosen and torque up the crank bolt (210Nm is tight)

((CLICK ON IMAGES TO ENLARGE ))

===Tools Required===

You will require a cut down 22mm socket to fit in the limited space between the crank pulley and the chassis (a 6 sided socket is stronger than a 12sided. Silverline do one for a couple of ££'s from Amazon)

[[File:Cambelt2.jpg|thumb|none|Gap]]
[[File:22mm Socket Marked.JPG|thumb|none]]
[[File:Cambelt4.jpg|thumb|none]]

You will also need a

. 1/2" breaker bar to loosen the crank bolt. As long as possible (don't try and use a ratchet handle, you'll break it and get a hernia to boot)

. a torque wrench capable of operating up to 210Nm (with a slim head if possible)

. A Rover K Series camshaft locking tool

===Method===

1. Run the rear of the car up on ramps if you have them and remove the rear undertray and diffuser. Loosen the RHS rear wheel nuts while the weight of the car is still on the wheel

2. Remove the spark plugs (this will allow the engine to be turned over much easier
using the crank bolt as required below

3. Jack up the RHS of car higher still and place axle stands at the B and C positions in the diagram (if you don't have ramps then jack and support with axle stands in stages, as the tilt on the car can easily cause it to slip off a jack on it own)

[[File:Jacking Positions.JPG|thumb|none]].

Try and get the car high enough that you can kneel with your head inside the rear wheel arch (when the liner is out) as this is a comfortable working position allowing you to reach into the engine bay through the arch

4. Move the ramp out of your way and remove RHS rear wheel

5. Remove RHS rear wheel arch liner

6. You may wish to remove the brake disc on the RHS rear wheel to allow greater access into the wheel arch when working (it is not necessary to do this)

[[File:Cambelt1.jpg|thumb|none|View with Liner Out]]

7. Loosen the pivot bolt and clamp bolt on the alternator

8. Loosen the adjuster bolt to move the alternator towards the engine and provide slack on the the belt. The bolt has a fine pitch so expect to turn it many times before the belt slackens (If you intend to refit the existing alternator belt, before undoing the adjuster bolt, mark the position of the clamp bolt on the slotted bracket, so that you know exactly where to tighten the belt up to on reassembly)

[[File:Alternator Diagram.JPG|thumb|none|Alternator bolts]]

9. Remove the alternator belt

10. Unbolt the upper cam belt cover and manoeuvre it upwards and out via the the engine bay (the cover to clam clearance is tight, but it will come out with minimum force if jiggled about a bit)

Ensure that you do not lose the rubber seal that press fits onto the bottom edge of the upper cover

[[File:Cambelt3.jpg|thumb|none|Top Cover Removed]]

11. Before loosening the crank bolt place a suitably sized screwdriver or allen key in the visible flywheel ring gear next to the drivers side driveshaft to prevent the engine rotating (I found an allen key much less likely to slip)

[[File:Allen Key Crank Lock.JPG|thumb|none|Crank Locked with Allen Key]]

12. From under the car and using the breaker bar with the cut down socket, loosen the crank bolt (you are likely to have to brace your knees/feet against the underside to gain enough purchase to undo the bolt. Folk on here have snapped breaker bars doing this, so take care)

13. Remove the crank bolt, the large washer (note orientation) and then the crank pulley

[[File:Crank Pulley and Bolt.JPG|thumb|none]]

14(a). Remove the lower cam cover

14(b). Replace the crank bolt (only) and hand tighten.

15(a). Before removing the cambelt the engine requires to be placed in a known positioned with No1 piston (closest to belt end) at 90deg BTDC. As a visual aid to help find 90 BTDC, place a long screwdriver/large tie wrap/clean garden cane etc etc down through hole where you removed the spark plug on cylinder 1. It will rest on the piston crown and rise and fall with the engine rotation as required in part 16 and indicate piston location and direction. ***Make sure that whatever you use is long enough so that it does not fall into the engine at piston BDC !!! ***

15(b). Its worth highlighting the camshaft sprocket alignment marks, the crankshaft sprocket alignment marks and the engine block alignment mark with some Tippex (or white paint) for ease of viewing

[[File:Cambelt5.jpg|thumb|none|Camshaft Alignment Marks]]

[[File:Cambelt6.jpg|thumb|none|Crankshaft and Block Alignment Marks]]

16. Remove the screwdriver/allen key from the flywheel teeth, and with the car out of gear. Turn the engine using a rachet/spanner on the crank bolt (only ever turn clockwise), until the camshaft and crank shaft alignment mark line up as above AND the visual aid in cylinder 1 shows the piston is half way up the cylinder on the rise. Camshaft sprocket marks should face each other in a line with the centre bolts of each shaft. The crank dimple marks should straddle the block mark.

[[File:K Alignment Marks.JPG|thumb|none|K Series Camshaft Alignment Marks]]

17. Replace the screwdriver or allen key in the flywheel and place the camshaft locking tool into place

[[File:Cambelt7.jpg|thumb|none|Cam Locking Tool]]

18. Mark the old belt/sprockets at both cams and on the crank. When the old belt is off, transfer these marks to the new belt (carefully count the belt teeth). When fitting the new, the marks will ensure it is not out by a tooth anywhere along its length (the K series will run without damage when the belt is out by a tooth either way but not very well!!).

[[File:Cambelt8.jpg|thumb|none|Belt to Sprocket Double Check]]

19. Unbolt the tensioner centre bolt, remove the tensioner and slide off the cambelt.

20. The engine mount prevents the old belt from being removed completely. There are two ways of getting the old belt out and new one in

20a (Thanks to Dave Andrews for this tip):
The easiest method is to remove one bolt on the engine mount at a time and weave the belt in between the bolts. Slacken both so that the engine drops by 12-15mm or so. Remove one bolt and push the belt into the gap between. Replace the bolt and tighten to where it was (I.E. 12mm gap), then remove the other bolt and push the belt the rest of the way through the gap. Reverse the process to get the new belt in, then do up both bolts to the correct torque.

[[File:Engine Mount.JPG|thumb|none|Engine Mount]]

20b The alternative method, is to place a trolley jack under the engine (use a piece of wood between to spread the contact load), jack the engine up slightly and remove the engine mount bolts completely. Takes a bit longer and if the engine moves ever so slightly back or forward it can be a PITA to get the bolts started in the threads again

===Waterpump Change===

21 If you intend to change the waterpump as well (and if you're in here already its probably worth it !!), now is the time to do it. Drain the coolant by undoing and hoses that enter both side rails at the rear of the car

22. Unbolt the old pump and remove it. (Expect more coolant to flow from the engine block). There are 6 bolts circled in the photo. The top left is bolted from the rear side, the bottom right is a pillar bolt (used for the front cover as well) and there are two dowels, squared in the photo. Check that the old rubber sealant ring was removed with the old pump and if there is any corrosion around the face/dowels remove with wet an dry paper. The block surface should be clean to allow the new pump to fit well

[[File:Waterpump Bolts.JPG|thumb|none|Waterpump Bolts and Dowels]]

23. Ensuring the new sealant ring is in place in the groove on the new pump and fit the pump (you can use some (proper) automotive RTV silicon to hold the new sealant ring in place if required). Tighten the bolts in stages alternating between diagonally opposite bolts to 10Nm

===Cambelt Continued===

24. Before fitting the new tensioner, it is advisable to mark the end of the tensioner wire pointer with a drop of Tippex/white paint to alow it to be seen clearer during positioning

[[File:Cambelt10.jpg|thumb|none|New Tensioner on Right with Pointer Marked]]

25. Fit the new tensioner into position and secure with the centre bolt but leave it loose enough that the tensioner will wobble quite freely to give some freeplay while fitting the new belt. Ensure that the wire loop on the tensioner is hooked behind the bolt on the block.

The tensioner lever (the part where the allen key fits, should be at the 9 o'clock position)

[[File:Auto Tensioner Wire.JPG|thumb|none|Tensioner Wire Hook Position]]

26. Fit the new belt onto the crank pulley first. If you marked the belt as per section 18 above, line up the mark on the belt with the sprocket mark. Fit the belt so that approx half of the width is on the sprocket/half is hanging off the front edge. Again this gives you more leeway/flex with the belt as you feed it on.

27. Keeping the long RHS of the belt taught, feed it over the RHS (exhaust) cam sprocket then over the LHS (inlet) cam sprocket, again lining up the white marks you placed on it earlier and again only pushing the belt on half way

[[File:Cambelt12.jpg|thumb|none|New Belt - Aligning Crank Sprocket Mark]]

[[File:Cambelt11.jpg|thumb|none|New Belt - Aligning Cam Sprocket Marks]]

28. Feed the belt up around the water pump then around tensioner. Once around all the mounting points you can then push the belt fully onto all the sprockets until seated fully

29. Tighten the tensioner centre bolt, not fully, but enough to pull it against the block

30 From the service manual:-

[[File:Auto Tensioner Setup.JPG|thumb|none|Auto Tensioner Adjustment]]

30a. "Tighten the centre bolt until it is just posible to move the tensioner lever"

30b. "check the belt is central around gears and pulleys

30c. "Using a 6mm Allen Key, rotate tensioner anti-clockwise and align the centre of the indent on the tensioner pointer to the index wire

ENSURE that the pointer approaches the index wire from above. Should pointer go past index wire, release tension completely and repeat tensioning procedure"

30d. "Ensuring that the pointer maintains the correct position, tighten centre bolt to 25Nm"

(It is quite difficult to hold the allen key on the lever and use a torque wrench in this location. If you tighten this bolt up using the "calibrated hand" method, do not overtighten the bolt.

31. Remove the cam locking tool and the crank locking allen key/scredriver and using a ratchet on the crank bolt, rotate the engine 2 turns clockwise. Check the tensioner pointer is still in the correct position

32. Remove the crank bolt, refit the cambelt lower cover.

33. Ensuring the mating surfaces of the crank pulley, washer, bolt and sprocket are clean, refit the crank pulley, washer and bolt. (Do not use a thread lock compound). Make sure the notch on the pulley is keyed to the crank before tightening the bolt hand tight

34. Replace the crank locking allen key/screwdriver and torque the crank pulley to 210Nm. This is a significant force even with a long torque wrench. Do not be tempted to just beef up the bolt with a big spanner, numerous instances of the the crank nose being worn away, the pulley undoing and the crank sprocket sliding off because of a loose bolt have been documented with the K series

35. Remember to remove the crank locking allen key/screwdriver !!!!

36. Refit the alternator belt

37. Refit the upper cam belt cover (be careful that the rubber sealing gasket on the lower edge is in the correct place. Its easily knocked off)

38. If you have changed the water pump, reconnect all coolant hoses and refill the system with new coolant.

39. I always turn the car over on the starter with the spark plugs removed just as a double triple check that all is well. (not advisable on cars with coil packs as they can be damaged. Better to remove the power to the fuel pump) If it doesn't rattle like a bag of nails :-), then refit the spark plugs and leads, start the engine

40. Lower the car and bleed the cooling system per the service manual or

http://wiki.seloc.org/a/Bleed_the_cooling_system

CHOPPER.

===NOTES===

1. Alternative methods used to lock the crank include having the car in gear and an assistant press on the brakes VERY hard. It has worked for some and it appears OK for loosening the crank bolt but when doing up any slipage will throw out the timing !!!

Another method to undo the crank bolt that has been used is jam the socket and breaker bar against the groung/something very rigid, and use the starter motor to turn the engine. The bolt being held will undo as the crank turns. Use this method at your own risk.... and make sure the car is out of gear when you do it

Another method to block the crank bolt when you remove/put the pulley :
[[File:manual.jpg|thumb|left]][[File:IMG_0065 (Personnalisé).JPG|thumb]]

* Make sure the car is out of gear

* Unscrew the starter (bolts n°25 & 27) and take off the rear closure plate (n°26).

* Then you have accesse to the flywheel... Now you need a strong cornered plate that you'll can wedge between the sump and the flywheel. Put it in the red position when you unscrew the pulley (like in the picture), put it in the blue position when you screw back the pulley...

* Just have to put back the starter and the closure plate when you're done.

2. There have been a small number if instances reported where the cambelt centre tensioner bolt has become seized to the block through corrosion/overzealous tightening or the use of thread lock. Before stripping the engine to find this may be the case (and you now have a car that is incapable of being driven to a garage/mechanic), you may wish to check the tensioner bolt will loosen. This is possible by removing the upper cam belt cover before all else and trying to move the bolt a quarter turn. If it moves, tighten it back up and follow the normal procedure above

Useful video:
http://www.mgf.ultimatemg.com/group2/engines/index.htm

Useful link to another guide fitting the manual tensioner
http://www.tadts.com/instructions/engine/100016.html

Quick Guide

Thread here: http://forums.seloc.org/viewthread.php?tid=314945&page=1#pid5349364

===Tensioner===

'''PLEASE ADD INFORMATION'''

Auto or Manual

I looked at the information on Eliseparts to ascertain if our engine was fitted with a manual or auto tensioner.
It sugested auto, i purchased an auto one but it turnd out to be a manual.
be warned, eliseparts will not allow you to return the miss purchased item and they stipulate this on line.

===See Also===

'''PLEASE ADD INFORMATION'''

[[Category:Lotus Elise]]
[[Category:S1]]
[[Category:S2]]

Remove the undertray

2023-03-05T17:58:38Z

Lithopsian: the front undertray is a smaller rectangular tray at the well ... front of the car - remove comments that actually apply to the front undertray

{{Infobox Timetools
|time = 5mins
|tools = 8mm Socket
}}

[[Image:Remove the front undertray step 4.jpg|thumb|left|Topside of front undertray from Elise S2]]
{{clr}}

== Procedure ==
<gallery>
Image:Remove the front undertray step 1.jpg|Remove the three screws (8mm socket) securing the undertray to the front clamshell
Image:Remove the front undertray step 2.jpg|This shows the rear lip securing the undertray.
Image:Remove the front undertray step 3.jpg|Remove the nine screws (8mm socket) securing the undertray to the chassis
Image:Remove the front undertray step 4.jpg|Now slide the undertray forward, so the rear edge drops out of the lip, and then backwards to remove from the car
</gallery>

== Refitting ==
Not easy to refit without positioning yourself under the car.

# From below, slide the undertray inside the clamshell.
#* Make sure it's the right way up!
# Key the rear of the undertray into the lip.
# Replace all 12 screws.
#* The rear three screws are secured with [http://www.loctite.com/int_henkel/loctite_uk/index.cfm Loctite].

[[Category:DIY]]
[[Category:Body]]
[[Category:Lotus Elise]]
[[Category:S2]]

Remove the front undertray

2023-03-05T17:56:53Z

Lithopsian: Lithopsian moved page Remove the front undertray to Remove the undertray: not about the front undertray

#REDIRECT [[Remove the undertray]]

Remove the undertray

2023-03-05T17:56:53Z

Lithopsian: Lithopsian moved page Remove the front undertray to Remove the undertray: not about the front undertray

{{Infobox Timetools
|time = 5mins
|tools = 8mm Socket
}}

[[Image:Remove the front undertray step 4.jpg|thumb|left|Topside of front undertray from Elise S2]]
The front undertray needs to be removed for a variety of reasons such as to [[replace the anti-roll bar]],

This undertray is very important as it brings rigidity to the whole front of the car.
{{clr}}

== Procedure ==
<gallery>
Image:Remove the front undertray step 1.jpg|Remove the three screws (8mm socket) securing the undertray to the front clamshell
Image:Remove the front undertray step 2.jpg|This shows the rear lip securing the undertray.
Image:Remove the front undertray step 3.jpg|Remove the nine screws (8mm socket) securing the undertray to the chassis
Image:Remove the front undertray step 4.jpg|Now slide the undertray forward, so the rear edge drops out of the lip, and then backwards to remove from the car
</gallery>

== Refitting ==
Not easy to refit without positioning yourself under the car.

# From below, slide the undertray inside the clamshell.
#* Make sure it's the right way up!
# Key the rear of the undertray into the lip.
# Replace all 12 screws.
#* The rear three screws are secured with [http://www.loctite.com/int_henkel/loctite_uk/index.cfm Loctite].

[[Category:DIY]]
[[Category:Body]]
[[Category:Lotus Elise]]
[[Category:S2]]