The Ultimate Guide to Choosing the Right Antifreeze

Antifreeze is a mysterious subject for many drivers. Believe it or not, there are people out there who think the only stuff you should be putting into your radiator is regular water. However, those who understand the importance of antifreeze aren’t necessarily entirely in the know either. Antifreeze color, additives, and type of technology they use are just some of the things most drivers aren’t informed about.

Today we’ll discuss different types of antifreeze, what this liquid is used for, how to tell which one to put in your car, and much more. Hopefully, by the time we’re done with this little guide, you should be well versed in all things coolant liquid related.

The Ultimate Guide to Choosing the Right Antifreeze

Antifreeze – the Life Force of a Healthy Engine

Modern engines are all about causing explosions and harnessing that power efficiently. It’s a fairly barbaric process, but one that we’ve mastered and one that has propelled us straight into the age of globalization.

That being said, even the most controlled combustion has side effects, one of them being heat. Different materials behave differently when exposed to high temperatures, but most don’t take it too well. An average engine is extremely touchy when it comes to handling temperature.

Running it too cold will increase the rate of wear while running it too hot leads to warped heads and other unfortunate issues. It would be best if you kept it right at the optimal spot in the temperature range. To do so, engineers have come up with sophisticated, coolant liquid mixtures based on antifreeze.

Contrary to what people from our introduction believe, water is not an appropriate coolant. Water alone will cause the engine’s metal components, such as the radiator and other, to corrode. To prevent corrosion, modern engines require distilled water mixed with antifreeze.

Antifreeze - the Life Force of a Healthy Engine

What is Antifreeze?

Antifreeze is a lifesaver when it comes to maintaining optimal engine temperatures all year. It’s a fluid that contains a mix of additives. These additives have two main functions. One of them is temperature regulation.

Maintaining the Right Temperature

Water, even distilled one used to make coolant, has a freezing and a boiling point of 0°C and 100°C, respectively. If you were to dump just water into your engine, you’d have it freeze during the winter, which is a massive issue, or boil when the engine goes slightly past its standard operating temperature.

By adding antifreeze to your coolant, you are essentially pushing the freezing point lower and the boiling point higher on the scale. That way, when you come out to crank your engine at sub-zero temperatures, you won’t push solid pieces of ice through the system.


Manipulating the boiling and freezing temp of water is done using glycol. Glycol is an alcohol-based compound that is used all over various industries to help regulate temperature. We can point out two different types of glycol used in modern antifreeze mixtures – Propylene Glycol and Ethylene Glycol. The difference between the two is considerable.

Propylene Glycol

Propylene glycol is the less toxic glycol of the two. It’s generally used all across various industries, mainly in those where there’s a chance of it being anywhere near food. That lack of toxicity has its downsides, though. Propylene isn’t as good as ethylene when it comes to temperature control.

Ethylene Glycol

On the other hand, we have ethylene glycol. Although far more toxic than propylene, ethylene is generally better in terms of efficiency. The only issue with ethylene is the fact that it will harm you if it enters your body.

Engine Coolant Antifreeze (1 Gallon)
Shop Now

Additional Additives

In addition to glycol, your average antifreeze also comes packed with all kinds of other additives. Antifreeze and coolants, in general, are often used to keep the interior of the engine, where the coolant passes, from corroding away.


If you’ve been researching antifreeze, you’ve probably run into these abbreviations – IAT and OAT. What are these, and what do they mean?

IAT and OAT refer to the type of corrosion protection used in antifreeze. The OAT stands for Organic Additive Technology while IAT stands for Inorganic Additive Technology. Former is the more modern tech often used in long-life coolants meant to keep running for many thousands of miles.

On the other hand, IAT has to be changed roughly every two years or 20,000 miles, depending on the type of antifreeze and your car make and model.

Both of these have their pros and cons. Back in the day, the color of the coolant would determine which type it was. That’s not really the case anymore. We’ll get to colors in just a moment.

If there’s one thing you should never do is mix IAT and OAT antifreeze. Doing so will cause damage to the cooling system in a fairly short time.

Engine Coolant Antifreeze (1 Gallon)
Shop Now

Coolant Color Gradient

With all that info laid out, let’s run through different colors of coolant real quick:

  • Green and Yellow – Green and yellow coolant often mark an older type of coolant that uses inorganic acids to prevent corrosion. You’re looking at a silicate and phosphate-rich mix that is designed for older cooling systems.
  • Orange and Red – These would be your modern OAT coolants that usually run ethylene glycol and are designed to last five years or 150,000 miles. Dex-Cool is an excellent example of a modern OAT coolant used in SAAB and other GM based engines. It’s important to know that OAT orange and red coolants are NOT compatible with older vehicles. Using an OAT coolant in a vintage car will rate away from all kinds of cooling system components.
  • Purple, Blue, or Pink – Coolants that have these colors are your wild cards. This segment of coolants is full of HOAT NOAT or POAT coolants, which represent various hybrid technologies. Unless you know for sure that your car requires one of these specific coolants, it’s best to use them with extreme caution.
Engine Coolant Antifreeze (1 Gallon)
Shop Now

Which Coolant Should Be In your Expansion Tank?

All of this can be confusing, especially if you just want to get your car filled and ready to go, with minimal involvement. So how should you choose the right coolant for your vehicle?

The absolute best thing to do is use whatever the factory is recommending. Some car manufacturers even sell their own certified genuine coolants, which makes life a lot easier overall.

Here’s a list of genuine coolants categorized by brand:

Genuine BMW Coolant – Blue

Genuine Mercedes-Benz Coolant – Blue (do not mix with early yellow coolant, requires flush)

Genuine Porsche G40-91-EF – Pink (most likely the same as Genuine VW/Audi but not confirmed)

Genuine Saab Coolant Dex-Cool Orange (made by GM AC Delco)

Genuine Volvo Coolant – Bluish Green (used to be straight blue, backwards compatible)

If your brand doesn’t offer a genuine coolant, you should always consult your service manual or local dealership.

What Happens If Your Has the Wrong Coolant in the System?

It’s not unheard of to get a car, even one of those certified preowned deals, that has the wrong coolant in the system. Your priority at this point is to get the coolant out of the car. It’s difficult to determine just what kind of damage, if any, was caused to the cooling system.

To get the old stuff out, you can use something like a genuine Mercedes-Benz citric coolant flush. The way products like this one are used is easy.

All you need to do is mix the coolant flush product with distilled water and run it through the system. Crank up the heat, so the flush goes through the heater core as well. Afterward, dump the flush liquid out and fill the system with the proper coolant. Make sure to bleed the system upon refiling it.

Citric Acid Cooling System Flush
Shop Now

What’s the Right Antifreeze to Water Ratio?

Finding the right ratio for your coolant should be easy. Most cars come with that information available in the user manual. Going with a 1:1 mix is always a solid choice. Adding one part antifreeze to one part, water ensures that you won’t have issues during the winter, no matter how cold it gets.

On a side note, if you live up north where the temperature drops way below zero, you might benefit from getting cold-weather antifreeze. Either way, consult your user manual and/or your local dealership for more current advice on this subject.

Engine Coolant Antifreeze (Orange) (1 Gallon)
Shop Now

Where to Get Genuine Coolant?

Here at, we offer a complete range of genuine coolants for various European makes and models. If you’re interested in finding the right antifreeze for your car, simply head over to our online store and input your car’s data.

In case you have any questions regarding Genuine brand antifreeze, please give us a call or reach out to us via email. Our customer support service is standing by to answer all and any questions you might have.

19 thoughts on “The Ultimate Guide to Choosing the Right Antifreeze
  1. Jim Hauck

    Good info!! Thanks
    You have A great site………..i have an older Volvo 1990 760 wagon w/turbo and want to start using parts mad especially for a Volvo- after market off brands don’t always work, I’ve Always had trouble with the starter motor dragging but we put off brands starters on in the past. i have a Bosch coming in from you now and hope it solves the problem.

    Thank you so much!

  2. Willie Dumas

    Good information. Someone top my blue coolant off with green in my Nissan juke. The dealer told me I need to have it flushed. I’ll be sure to have it done soon before it gets cold.

    • Adam Goral

      Good idea, some coolants are definitely compatible, but why risk it. Especially when you can have the piece of mind of a fresh coolant flush that does favors to all aspects of your cooling system.

  3. Tony Rodolfo

    As far as using OAT in old cars and having it eat copper and solder in the radiator, that well could happen if you left the stuff in there for way longer than 5 years. Otherwise, the Ph can be checked from time to time if you are all that concerned. If it gets below 7or 8 ph (more acidic is lower number) then change it out. If you change it at intervals recommended on the label, and mix the undiluted with distilled water, not tap water, it is not going to eat anything.

  4. yasser iqbal

    hi I have pink coolant in my range rover sport 2006, I have brought a blue antifreeze it said was compatible with my engine. is that right I can use the blue one?

  5. P.Bowler

    Can you help please.
    I am replacing the antifreeze in my 2003 Audi 1.8 A3. It has dark red colour in it now. Our local work shop is insisting I use green antifreeze. I believed I should be using pink.
    Am I correct or is the workshop correct. I have just received an email from them saying they have sent green.
    Thanks P.B. New Zealand.

    • Adam Goral

      No sir, with the materials used in the cooling system of that 2002, the standard green stuff will work just fine. Type of coolant has little to no effect on the cooling capacity, only the type of anti-corrosion capabilities depending on the types of metals in the cooling system.

  6. Sergio Ulloa

    Hi Adam, good and usefull info, thanks!!! I have a 2000 MB ML320, actually I am the 2nd owner, but I´m not sure if I am using the right coolant. There is a green on it. Could I use the Krynex from Shell, as my mechanic says? Or definitelly I should use the blue one?
    Thank you very much

    • Adam Goral

      At some point it may have been changed to a green coolant, but the correct Genuine Mercedes coolant is, as you said, blue. I have never heard of Krynex before, it might not be a North American brand, but I can tell you that if you do switch over coolant it’s best to use the OEM Genuine Mercedes coolant which is not that expensive. You should only need one, and mix it 50/50 with distilled water. Do NOT mix the colors, if you are going to put the right stuff in, you have to follow these steps:
      Drain all the green coolant out
      Seal the system
      Fill it with distilled water ONLY
      Bring the car up to temperature with just the water and make sure the air bubbles are bled
      Drain the water out
      Fill the system back up with a 50/50 mix of Genuine Mercedes Coolant and distilled water.
      This makes sure that you won’t mix the different types of coolants, which can lead to crystallization and clogs as described in the blog post.

    • Adam Goral

      These are two minorly different styles of coolant as you are well aware (OAT vs HOAT). What will happen if you mix? I can’t say for sure. Are you willing to turn your engine into the science experiment and see? Since HOAT Coolants are hybrid OAT’s with silica added, you would probably be fine, but it’s so easy to just do a flush and make sure everything is kosher, why not do it right? The absolute steadfast no-go is mixing a OAT or a HOAT with an Inorganic IAT. If you just need to top up a slightly low cooling system, most of the time plain distilled water is the best solution. There’s no way you can dilute it enough to inhibit its antifreeze component with an occasional splash of water unless you live in Siberia and/or enjoy regular week long bouts of very sub-zero degree temperatures.

  7. Jackie

    Hi. I have an Audi A 1 TFSI 2013
    It has pink coolant. When checking it says I need the blue. What should I do.
    I know I can’t mix them but has the wrong colour been put in by the previous owner

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.