Understanding the Different Antifreeze Types for Your Car

Are you looking for the right engine coolant for your car? Keep on reading this post to know the different antifreeze types and how they’re made.

Are antifreeze and coolant the same thing?

What kind do I need for my engine?

Why is the coolant green? 

If any of these questions have crossed your mind, you’re not alone. The mechanics of your engine are complicated and little things, like antifreeze, make a huge difference in how the vehicle runs. 

This guide breaks down antifreeze types (and their colors) so you know what kind to put in your baby. 

Antifreeze vs Coolant 

Antifreeze is coolant. Coolant is antifreeze. Don’t let the names trick you up. 

Engine coolant is a mix of ethylene glycol and water. Nearly all engines use a 1:1 ratio of coolant: water.

One thing to bear in mind with modern coolants: The jugs you buy at the store are pre-diluted. In the past, coolant was sold as a pure substance that you would have to dilute with water at home before you put it in your car. 

Pre-diluted coolant is more convenient. 

Why Coolant Is Important 

The coolant keeps your radiator from freezing in the winter and overheating in the summer.  It protects the engine and cooling system from corrosion.

Different types of engines require different coolant types. Picking the right one will make your engine run cleaner and more efficiently. The wrong one will be a huge headache later. 

Flushing and sealing your coolant system keeps everything running right. 

Common Antifreeze Types by Color 

Water and antifreeze are both colorless.

Manufacturers started adding colored dye to the mixture in order to differentiate between the coolant and other engine fluids. If your car was leaking a blue fluid, it meant one thing. If it was leaking a pink fluid, it meant another. 

As time went on, and more types of antifreeze were released to the market, manufacturers started added specific colored dyes to specific types of antifreeze so consumers could tell the types and brands apart. 

This guide breaks down the most common types of antifreeze by their commonly associated colors. Not all types of antifreeze are covered. 


If you have a green coolant, you have Inorganic Acid Technology (IAT) coolant. This type of coolant is the original type of coolant on the market. This means that if you drive an older model car, it likely still uses green antifreeze.

This type of coolant is sometimes referred to as conventional low-silicate coolant. This is because it uses silicates as corrosion inhibitors. 

Historically, a green-dyed coolant was designed for cars and small trucks. You would have to dilute the coolant with water and “pre-charge” it with supplemental coolant additives. These additives were designed to protect engine cylinders from corrosion. 

Now, the coolant comes diluted and pre-mixed with all the additives already in it. As long as you change the antifreeze every 24k miles or so, you should be fine. If you choose to push the life of the coolant beyond that, you will want to mix in those additives as specified by the engine manufacturer.


An orange coolant typically indicates that you are looking at Organic Acid Technology (OAT) coolant. This type of coolant uses organic acids as an inhibitor. 

This is the type of coolant usually required for GM, Saab, and VW vehicles.

OAT coolants do not have nitrites added. Contamination with nitrite – such as if you were to add the wrong type of coolant to the system – can drastically reduce the performance life of the OAT coolant. 

Orange-dyed coolants typically protect an engine for 600k miles, as long as they remain pure and uncontaminated. 


A Hybrid OAT (HOAT) coolant is also an option. It is typically dyed yellow. 

This type of coolant mixes technology from the first two to create a low-silicate, nitrite technology. It contains both silicates and organic acids as inhibitors.

Ford, Chrysler, and some other European companies recommend this type of coolant for their cars.

HOAT coolants, like the IAT coolants, require additives mixed back into the coolant system every 25k miles, or as specified by the engine manufacturer.

HOAT coolants formulations are not compatible with OAT coolants because they do contain nitrites. They should not be mixed together.


If you have a red coolant in your cooling system, you have an Extended Life Coolant. This coolant is recommended for use in Toyota, Scion, and Lexus.

It can be used in any engine requiring an OAT engine coolant. 

Red coolant offers 150k miles of protection. Like other OAT coolants, don’t mix it with nitrate or silicate-based antifreeze.

Color Can Lie: Always Read the Label

No one is regulating the color of your coolant. This means that, while it was a good indicator of the type historically, color is not a reliable predictor of what kind of coolant you have kicking around in your garage now.

For example, OAT coolants are usually orange but, depending on who manufactured it, the coolant can look more yellow or red. Some manufacturers have opted for entirely different color schemes for their coolants. Honda has decided to make all of its coolants, regardless of technology, blue. 

You need to carefully read what the bottle says. It’s not safe to rely on the color.  Always double-check your owner’s manual to determine the type of coolant your system needs.  

Other Antifreeze Types By Continent of Origin

Other than color, which is not the best indicator, there is also the country of origin of the car. The country that makes the car is a much more consistent indicator of what type of coolant your car will need. 

Here are a couple of other coolant choices (again, the list is not all-encompassing): 


Europa is generally plagued by a hard water problem. This means that in order to meet European regulations, the coolant would need to be phosphate-free. 

Calcium and magnesium, which are common in hard water, react with phosphate inhibitors to form calcium or magnesium phosphate. These chemical reactions can cause scale formations on engine surfaces.

Europe uses a form of HOAT coolant that is phosphate-free. European HOAT contains a mix of silicates and carboxylates. 

This form of HOAT is recommended for BMW, Volvo, Tesla, Mini, other vehicles. This European coolant disregards a color designation. Instead, Europe requires each manufacturer to create one specific color of coolant.  


Asia has the opposite need of Europe. In Asia, a phosphated HOAT (P-HOAT) is required. 

Problems with poor heat transfers have led to a ban on silicates as corrosion inhibitors in coolants. To protect engines, Asian manufacturers have adopted a mix of carboxylates and phosphates as corrosion inhibitors. 

P-HOAT is used in most Asian vehicles, including Toyota, Nissan, Honda, Hyundai, KIA & others. Typically these coolants are pink or blue.

Your Coolant System Requires Upkeep 

Whatever antifreeze types you use, it will degrade over time as the ethylene glycol breaks down. The breakdown of the coolant occurs more quickly in engines that operate at high temperatures. 

Once a coolant has degraded, the metal of your engine is at risk for corrosion.

If you have an old jug of coolant sitting around the garage and you aren’t sure if it’s good anymore, use a refractometer to measure the glycol: water ratio. This ratio will tell you the level of freeze protection and the concentration of corrosion inhibitors. 

When in doubt, buy new coolant. Using a high-quality coolant and performing basic maintenance will protect your engine for the long haul.  

Check us out here to learn more about Irontite products and see how they can protect your engine alongside regular maintenance. 

Related Articles:

 What Is Antifreeze and What Is It Used For?

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