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What is antifreeze, what types are there, and how to replace it in a car?

19th October 2021 Print

The antifreeze in your engine helps regulate temperature when your engine is in extreme conditions. It is a colored liquid mixed with water. Temperature changes outside change the amount of antifreeze pumped through the engine block to maintain an even operating temperature. Antifreeze, however, does more than regulate temperature. It also maintains proper fluid levels and can also prevent corrosion.

There are three types of antifreeze that car companies use: Organic Acid Technology (OAT), Inorganic Additive Technology or IAT, and Hybrid Organic Acid Technology (HOAT). Antifreeze like IAT is commonly used in older cars. Unlike newer formulas, it requires frequent replacements every two years or 24,000 miles.

Types of antifreeze by color 

There are multiple colors of antifreeze. For people who are unfamiliar with the meaning of the colors, this can be confusing. To help you better understand why the liquid comes in so many different colors, we will break it down. Various colors are used, including blue, yellow, green, red, pink, turquoise, orange, and purple.

A vehicle can run any type of antifreeze that is safe for aluminum, so you should choose the kind based on what kind of protection you need from it (preventing corrosion and preserving the metals and aluminum parts) and how often you want to flush your antifreeze system.


You will typically find orange antifreeze when you are looking at Organic Acid Technology (OAT). Antifreeze in this category contains organic acids as an inhibitor. 

Antifreeze of this type is usually found in GM, Volkswagen, and Saab vehicles.

Antifreeze made by OAT does not contain nitrites. The performance life of the OAT antifreeze can be drastically reduced by contamination with nitrite - for example, if you were to add the wrong type of antifreeze to the system. 

As long as the antifreeze remains pure and uncontaminated, orange-colored antifreeze usually lasts for 550k miles. 


Hybrid OAT antifreeze is typically yellow in color. Silicate and nitrite technologies are combined in this type of antifreeze to create a low-silicate, nitrite antifreeze. This type of antifreeze contains silicates and organic acids to act as inhibitors. Some European manufacturers, such as Ford, Chrysler, and Mazda, recommend this type of cooling fluid.

OAT antifreeze contains nitrites, which means they are not compatible with HOAT antifreeze. In addition, as with IAT antifreeze, HOAT antifreeze needs additives added to them every 24k miles or as instructed by the engine manufacturer. They shouldn't be combined.

How to change antifreeze for cars?

Make sure to change the antifreeze in your car if you want it to last longer. It's recommended to change the antifreeze in a car at least once each year. There's no problem changing the antifreeze.

- Antifreeze must be changed with the following equipment
- Manuals for service and repair
- Drain pan for about 2-3 gallons
- antifreeze and antifreeze 50-50
- Pliers

If you decide to change your antifreeze/antifreeze liquid, make sure that the color you choose is compatible with your car or that you can use a different color.

Antifreeze should be drained completely and topped off with water/distilled water, then let it circulate fully before draining it again. This process should be repeated 2-3 times. This helps flush the antifreeze from your cooling system's deepest nooks and crannies and enables any old deposits in your cooling system to dislocate.

Make sure you use the tips above and follow the 50-50 ratio when adding the new antifreeze. It would be best to follow the instructions on the box to make the  correct mix.

Although it may seem good to add more liquid to an antifreeze's composition than water, in reality, this reduces its effectiveness. There are a few problems you may encounter while replacing antifreeze, the most common one being: Radiator Leak and Cracks

Radiators leak engine antifreeze when they crack. If your radiator cracks, your car won't let you ignore it. The car will either start running hot or you'll see puddles underneath it.The source of some radiator leaks isn't always obvious. The radiator needs to be inspected with particular attention to the bottom and radiator seams.

The system should be heated and recirculated every 30 days at the very least to prevent deposits and to maintain high levels of protection. This applies to all antifreeze liquids.

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