How To Pick The Right Coolant For Your Car 

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Mercedes-G65-AMG-Engine

Buying coolant for your euro car can be an ordeal. What type do you get? How much of it do you need? Where can you get it? We've got your answers and some data to help you make the right call for your car.

Many of us have tried to buy coolant locally but unfortunately, the typical automotive stores almost never carry the right kind. This is because general automotive stores will stock coolant that works in the most amount of cars, be they domestic or Japanese imports that most people are driving. You may ask yourself, "why is there a difference"? Shouldn't all coolant work in all cars?

The short answer is no, not all coolant is created equal. The generic green or orange coolant may be compatible with your car, but that doesn't necessarily mean you should use it. Here's why:

Compound

Coolant, essentially, can be plain distilled water as water is a very effective coolant. However, the downfall of water is that it doesn't have the correct corrosion inhibitors and lubricity for the components in your cooling system. It also doesn’t do a great job at protecting the engine's internal components against freezing. If you paid attention in science class, water freezes at 0 degrees Celsius or 32 degrees Fahrenheit, depending on which side of the pond you’re on.

Coolant (also known as antifreeze) is the best of both worlds. It lowers the freezing point of water and raises it’s boiling point, all while providing excellent corrosion protection and proper lubrication.

Most modern coolant/antifreeze formulas contain glycol (which lowers the freezing point and raises the boiling point), along with corrosion inhibitors and dyes (orange, green, red, or blue). The most common dilution is 50:50 with distilled water.

There are three basic types of coolant available today dependent on the corrosion inhibitors used:

·Inorganic Additive Technology (IAT)
·Organic Additive Technology (OAT)
·Hybrid Organic Acid Technology (HOAT)
·Hybrid Organic Acid Technology (Si-OAT)

Inorganic Additive Technology (IAT)

This type is formed with silicates and phosphates. Silicates provide a protective film that quickly forms on the inside of the system and does a great job protecting it from corrosion. The downfall of this technology is that the additives deplete in a relatively short amount of time. This means that the coolant loses effectiveness and fails to protect the internals after a few years. This type of coolant should be flushed in 2 year intervals in order to maintain proper functionality.

Following this maintenance schedule will ensure the prolonged life of your cooling system.

Below is a radiator with clogged ports due to build up of silicate. This can lead to an overheating engine, so consider the perceived cost benefit you get from skipping coolant flushes versus the cost of a new engine.

radiator-dirty-coolant

Organic Acid Technology (OAT)

The newer OAT coolants work a bit differently than the older silicate-based IAT coolants. First off, these coolants don't have any silicates or phosphates. They contain organic salts to protect the cooling system. This means that their service life is extended. This category of antifreeze cannot be used in systems containing yellow metals, meaning older cars with copper and brass cooling system components can not use this type of coolant. Newer cars with aluminum engines and cooling system components are probably OK.

OAT technology was designed in relation to an environmental backlash by various organizations to bring to market coolant products that do not pollute the environment—just as IAT coolants have been doing. OAT introduced longer intervals and thus reduced maintenance costs and a lower environmental impact. Unfortunately this coolant's performance was not as good as the IAT coolant it was slated to replace. OAT coolant takes a lot longer to coat the system in order to protect it, and any short period of time being exposed to water or moisture would corrode the metal.

Hybrid Organic Additive Technology (HOAT)

HOAT is a term that combines IAT technologies and OAT technologies together. Generally designed for engines that have iron blocks and aluminum heads, most modern coolants for European cars are created with this technology. The European formulas do not contain any phosphates either as they do not work well with the hard water found in Europe.

Silicate Organic Additive Technology (Si-OAT)

Performance issues with silicate-free OAT led to the development of a new high-performance antifreeze/coolant technology called Si-OAT (Silicate Organic Additive Technology). Basically, this coolant is the best of both worlds—great protection with silicates being re-introduced and long life with OAT technology. These new Si-OAT products are backwards compatible as well.

Some facts to consider:

  • We can refer back to the late 90’s and early 2000’s when most VAG products were filled with G12 coolant that removed silicates from the formula. The formula over time began to eat away gaskets and metal components within the cooling system and had led to many leaking heater cores among other cooling system woes. (They switched out to Si-OAT on the next generation of cars.)
  • Most VAG products in this era, and until today, had Silicate packs built into the expansion tanks that were designed to provide more protection from the system.
  • BMW, Mercedes, and Volvo have been using IAT coolant since the 80’s. Now the formulation changed to a HOAT fluid. Not much has changed in the composition or the specification since. The intervals that they need to be replaced at have however been extended all the way from 2 years in the 80’s initially to 3 years to 4 years in the 90’s to now “LIFETIME” in virtually all BMW applications. Guess what is the weak spot of a modern BMW … The cooling system! We wonder why?
  • Mercedes had also installed silicate packs into their expansion tanks to help the cooling system maintain it’s properties over time and extend it’s effectiveness.
  • Electrolysis is a fun by-product of not changing coolant on time, and it has some very negative impacts on all things aluminum. As you can see in the picture below, electrical current traveling through the coolant seeking a path of least resistance found it’s way out by creating new passages. Not a good thing long term for your engine and all aluminum parts in that system.

Thermostat-Housing-electrolysis

Can IAT, OAT, and Si-OAT coolants be mixed?

A simple answer is that you CAN NOT mix IAT and OAT fluids. You can however top off with the correct fluid rated for your car regardless of the color it is produced in. You can mix Si-OAT fluids with previous generations of fluids as they are backwards compatible.

Below we list the different coolant compatibilities and what we offer to service your car:

G30, G33, G34, G40, G44 should all be compatible with each other.

G05 and G48 should be compatible with each other.

*Glysantin Data is used since it is a BASF company that designed most of the products that correspond to the following manufacturer specifications.

  • Glysantin G05 (HOAT, Silicates)
  • * pH-value 6.5
    Chrysler MS-9769
    Mercedes-Benz DBL 7700.20 Page 325.0
    John Deere JDM H 24
    Leyland BLS.22.AF.01
    Ford North America WSS-M97B51-A1
  • Our offer:
    Rowe: Rowe AN Antifreeze
    (G05 can be mixed with G48 coolant regardless of color. It is advisable to switch to G48 due to current availability after performing a full cooling system drain, flush and re-fill)
  • Glysantin G48 (HOAT, Silicates) (VW G11, Volvo, BMW, Mercedes)

 

 

  • Glysantin G30 (OAT, No Silicates) (VW G12, G12+)
  • * G30 pH-value 8.2 - 8.6
    Audi since 8/96 TL 774-D/F
    Mercedes-Benz DBL 7700.30
    Ford WSS-M 97B44-D
    Seat since 8/96 TL 774-D/F
    Skoda since 8/96 TL 774-D/F
    VW since 8/96 TL 774-D/F
    Porsche
  • Our offer:
    Rowe: Rowe AN 13 Antifreeze
    (Due to G12 no longer being made, if the system needs a top off it is not recommended to mix antifreeze types. A drain, flush and re-fill is suggested with the latest fluid)

 

  • Glysantin G40 ("Si-OAT" - hybrid organic acid technology)(VW G12++)
  • * pH-value 8.2 - 8.6
    Audi: TL 774 G
    Bentley: TL 774 G
    Bugatti: TL 774 G
    Cummins: CES 14603
    Lamborghini: TL 774 G
    MAN (built as from 12/2011): MAN 324 Typ Si-OAT
    Mercedes-Benz (Trucks built as from 10/2011): Specification 325.5
    Seat: TL 774 G
    Škoda: TL 774 G
    VW: TL 774 G
    Porsche (built as from 1997): 911, Boxster, Cayman, Cayenne, Panamera
  • Our Offer:
    Rowe: Rowe AN 13 Antifreeze

 

  • Glysantin GG40 ("Si-OAT" - hybrid organic acid technology)(VW G13)
  • * pH-value ~8.5
    Audi: TL 774 J
    Bentley: TL 774 J
    Škoda: TL 774 J
    VW: TL 774 J
    Porsche: TL 774 J
    ASTM D3306
    CUNA NC 956-16
    BS 6580: 2010
  • Our offer:
    Rowe: Rowe AN 13 Antifreeze
    Genuine VW: Genuine VW Antifreeze

Volkswagen Coolant Compatibility Chart (G11, G12, G12+, G12++, G13)

VAG-Coolant-chart

Anything in red would signify what you can not mix. Anything in green is mixable. Keep in mind when topping off a G11 or G12 filled system with a newer product the color of the coolant will change to a dark brown color. The properties of that newer fluid will also change and no longer hold the original cooling properties.

Mercedes Coolant

  • A previous version of Mercedes coolant is no longer available:
    Q1030002 which falls under the 325.0 spec sheet and is Yellow. G05 (HOAT, Silicates)
    Two current versions of Mercedes coolant are available:
  • Q1030004 which falls under the 325.0/ 325.1 spec sheet and is Blue. G48 (HOAT, Silicates)
    - This coolant is backwards compatible with Q1030002 (yellow) and CAN be mixed.
    - However, due to the age of Q1030002 if original fill, it should be drained, flushed, and replaced with the modern Q1030004 fluid.
  • Q1030005 which falls under the 325.5 spec sheet and is Pink. G40 (Si-OAT)
    The difference in this latest fluid between the Q1030004 is that now it is made as a Si-OAT fluid. It is a hybrid of technologies making it last longer.
    - This coolant should NOT be mixed with the older Mercedes Benz coolants since the properties of the coolant will be affected and not perform as advertised. Accelerated internal wear on coolant components can be present as a result.
    - You can use the previous Q1030004 fluid in a Q1030005 factory filled system ONLY IF the system is drained, flushed, re-drained and then filled with Q1030004. The protection is nearly identical however the Q1030004 is not designed to last and perform as long as the new Q1030005.

BMW Coolant

BMW is very simple when it comes to coolant. The BMW spec is BMW N 600 69.0 and it is found in the G48 type coolant. It is also compatible to be used in nearly all Volvo applications, Mercedes Q1030002 and Q1030004 applications. It also works in early VW applications under the TL 774-C specification or more commonly known G11.

Hopefully this write-up helped shed some light on the confusing coolant debate. If there's anything we missed, let us know in the comments below.

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