How To Pick The Right Coolant For Your Car 

Mercedes G65 AMG Engine

Coolant. What type? How Much? Where to get it? We've got your answers. 

Many of us have tried to buy coolant for our beloved European car but unfortunately, the typical automotive stores never carry the right ones. Either that, or they've asked too many irrelevant questions for us to bear—like what type of interior you might have, or what color your car is. 

Surely a young, inexperienced kid behind the counter wouldn’t know better, and we get that. But not all coolant is created equal. Just because the green generic coolant is said to work by the kid behind the counter, doesn't mean we should actually use it.

Coolant, essentially, can be plain water. And 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 internals 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 lubcriation for all moving parts.

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.

Now it gets interesting (boring).

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 is formed with silicates and phosphates. Silicates provide a protective film that forms quickly 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. Guess what? Coolant flush time. Often! It is a good idea to flush the system in 2 year intervals. IAT think old school, iron, brass, and solder.

Following an old school maintenance schedule will ensure your components last a very long time.

Below is a radiator that shows clogged ports due to build up of silicate. This can lead to overheating which equals $$$.


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 any older car with copper and brass cooling system components. Newer cars with aluminum engines and cooling system components are probably OK. You will have a difficult time finding a modern car with old school metals anyway. When it comes to OAT, think Aluminum.

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 the environmental impact. Unfortunately, although this coolant can last longer, it’s performance was not as good as the IAT coolant it was slated to replace. The 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 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. Think BMW, Mercedes, Volvo. 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, 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.

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.


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.

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)

* pH-value 7.2
Audi TL 774-C
BMW BMW N 600 69.0
Caterpillar* SEBU6250-12
Mercedes-Benz DBL 7700.20
Opel/General Motors B 040 0240
Porsche TL 774-C
Saab 6901599
Seat TL 774-C
Skoda TL 774-C
VW TL 774-C

Our offer:
Rowe: Rowe AN Antifreeze
Genuine BMW: BMW Antifreeze
Genuine Volvo: Volvo Antifreeze
Genuine Mercedes: Mercedes Antifreeze

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

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

Anything in red would signify that 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.

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Topics: Culture, Do-It-Yourself

About the Author: Michael Delikat
Automobile aficionado. I really enjoy the engineering behind many of the automotive products out today. This includes mundane things which no one really looks at like filters, fluids along with suspension design and behavior. I also enjoy all things rare and produced in low numbers. Being a Service Manager at independent specialists and working at the dealership gives me valuable insight as to how cars get repaired, what products work, and what makes customers happy.
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