What Coolant Does My Car Need? (Explained!)

Coolant is an essential component of the cooling system. It circulates around the engine and absorbs the heat, thus preventing the engine from overheating. If you owned more than one car, you may have noticed that on some cars the coolant is green and on some it is red. Well, what is the difference between the two and what coolant does your car need?

In this blog post, I will be talking about types of coolants and how to choose the correct coolant for your car.

Key Takeaway

  • To choose the best coolant for your vehicle, you need to find out if your engine is made out of iron or aluminum. Engines made out of iron need IAT coolants (green coolant) and aluminum engines need OAT (orange) coolant.
  • Each vehicle requires a specific type of coolant depending on the material of the engine.
  • If you add the wrong type of coolant, a chemical reaction between the different coolants will clog up the radiator and a coolant flush will be needed.

What Coolant Does My Car Need?

What Coolant Does My Car Need (Explained!)

Coolant is a critical element of the vehicle’s cooling system. The primary function of a coolant is to absorb the heat from the engine to prevent it from overheating. The coolant provides freezing protection and protects the engine from boiling over. However, another commonly overlooked property of the coolant is corrosion protection.

Engines are made out of various metals such as cast iron, steel, cast aluminum, brass, copper, and magnesium alloys. The coolant helps inhibit corrosion for cooling system metals through a wide range of temperatures. Each type of coolant is designed to be used on a specific type of engine. So, what coolant does your car needs?

The generation of coolant colors started more than two decades ago and still continues to this day. Different brands create different types of coolants and dye them in different colors. But the colors of the coolants aren’t that much important. The technology behind the coolants is much more important.

To understand which coolant your car needs it’s important to know the type of metal that your engine is made out of. Older vehicles with iron-made engines use IAT coolants which is short for inorganic additives technology, or green coolant. Organic acid technology coolants or OAT are used for light-duty and medium-duty vehicles with aluminum gasoline and diesel engines and are usually orange, red, or yellow. The third type of coolant is made as a mix of IAT and OAT and is used mostly for Asian-made vehicles.

If you are not sure what type of engine your vehicle has, you can take a look at the owner’s manual. There you will find all the information that you need in order to select the best coolant for your vehicle.

Does My Car Need a Specific Coolant?

What Coolant Does My Car Need (Explained!)

Yes. Each vehicle requires a specific type of coolant. Coolants are designed to meet the needs of different types of engines. This being said, if your engine is made out of aluminum, it needs to use a coolant based on organic acid inhibitor technology (OAT) made out of organic corrosion inhibitors because this type of coolant offers protection against corrosion for aluminum engines.

If your engine is made from cast iron, you should use coolant based on inactive additive technology (IAT) made out of ethylene glycol and phosphate. This type of coolant provides protection against corrosion for engines made out of cast iron blocks and other metals.

Modern vehicles, on other hand, use coolants that are made based on hybrid organic acid technology (HOAT) and are made out of silicates. This type of coolant is a combination of OAT and IAT coolants and offers protection for modern aluminum engines.

Using the wrong type of coolant or mixing two different coolants can cause a chemical reaction between the two liquids which results in the coolant gelling up and causing obstruction in the cooling system. Without a proper coolant, your engine will overheat.

What Happens If You Put The Wrong Coolant In Your Car?

About 70% of the energy and gasoline in engines gets converted to heat. Many people think that the job of the coolant is just to remove the heat and prevent the engine from overheating. However, that is just partially true. The coolant also has the job to leave sufficient heat so that the engine can perform properly. On top of that, the coolant offers protection from corrosion on the metal parts of the engine. But what happens if you put the wrong coolant in your car?

If you add the wrong coolant to your car, it will come to a chemical reaction between the two coolants and they will gel up. This will lead to clogging up the cooling system and engine overheating. If you have performed a coolant flush and then you added the wrong coolant to your car, over time, the metal parts of the engine will corrode because the coolant that you added may not provide protection against corrosion to your specific engine.

Basically, each engine needs a specific type of coolant. Some engines are made out of cast iron, some are made out of aluminum, etc. Now, since the coolant circulates inside the cylinder head and engine block, it gets in contact with the engine metals. So, different types of coolants offer protection against corrosion for different types of materials.

If your engine is aluminum and you are using a coolant that provides protection for iron engines, you will end up with a corroded engine. Vice versa, if your engine is made of cast iron and you are using coolant for aluminum engines, it will only harm your engine.

Does It Matter What Color Coolant You Use?

It does matter what color coolant you use for your vehicle, however, the color is just dye. The more important thing is the technology that each coolant has to offer that really matters. Manufacturers use different colors for the coolants so you don’t mix them easily.

The coolant circulates through pipes within the coolant system and passages within the cylinder head and engine block. As the coolant passes through the engine, it absorbs just enough heat so the engine won’t overheat. But, it also leaves enough heat so that the engine doesn’t get cooled down a lot. This is just one of the purposes of the coolants.

The more important purpose of the coolant that many people don’t know is the corrosion protection that it offers to the engines. Since coolant goes directly through the engine, if the wrong coolant is used, it can easily corrode those parts of the engine which will lead to engine failure. Since engines are made out of different materials like cast iron and aluminum, there are different types of coolants for each engine.

The older vehicles have engines made out of cast iron and they require a coolant that uses the inactive additive technology that is based on ethylene glycol and phosphates. This type of coolant is best for those engines and if it’s used on engines made out of aluminum, it won’t protect them from corrosion.

For aluminum engines, you need coolant that is using organic acid inhibitor technology based on organic corrosion inhibitors. This specific coolant provides corrosion protection only to aluminum engines, and not cast iron engines.

Can I Mix Coolant Colors?

No, you shouldn’t mix coolant colors because mixing coolant colors for an extended period of time creates a brown grit that will clog the thermostat, the radiator, and the water pump. When different color coolants mix, it comes to a chemical reaction and the byproduct is grit that can restrict the flow of the coolant and lead to engine overheating.

When you are looking at different coolants, you may only notice the difference in color. However, there is more than meets the eye. Different color coolants have different technologies, As vehicles developed over the years, so did the coolants. Different coolants offer different protection against corrosion, heat, and freezing point,

Green and yellow coolants made before the year 2000 are using IAT (Inactive Additive Technology) based on ethylene glycol and phosphates. Ethylene glycol has a high boiling point and a low freezing point. The phosphate offers protection from corrosion on cast iron blocks and other metals. This coolant lasts around two years before it needs changing.

Orange and yellow coolants made after the year 2000 are using OAT (Organic Acid Inhibitor Technology) based on organic corrosion inhibitors. The organic acid inhibitor coolants are great for engines that are made of aluminum. However, the OAT coolant does not provide protection against corrosion for copper or brass. This coolant will last up to five years.

The modern type of coolant comes in different colors such as yellow, purple, blue, pink, and orange, and uses HOAT (Hybrid Organic Acid Technology) and is basically a combination of IAT and OAT coolants. The main ingredient of HOAT coolant is silicate which offers protection for aluminum engines. This is the latest technology when it comes to coolants. It is made to last over five years or 150,000 miles.

Is It OK To Mix Old And New Coolants?

It is okay to mix old and new coolant as long as the old coolant isn’t contaminated and you are adding the exact same type. Each coolant is made based on different additives and mixing two different types of coolant will cause the coolant to gel up and block the cooling system.

Can I Just Add Any Coolant To My Car?

No, you can’t just add any coolant to your car because each engine requires a specific type of coolant. Engines made out of iron require IAT coolants and aluminum engines require OAT or HOAT coolants. If you just add any coolant to your car, not only you are risking corrosion, but two different coolants can actually gel up and clog the cooling system.

Bob Semana

Hi there, I am a Mechanical Engineer that specializes in AC, Alternators, Batteries, Cooling systems, and Drive Train issues.

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