Can I Use Green Coolant Instead of Red? The Differences

One confusing topic with car owners is the green vs red antifreeze. Many people need to understand why coolants come in different colors and the difference between these fluids.

In this article, we will answer the question, can I use green coolant instead of red? We will also examine whether the coolants can be mixed and how to solve a mixed red and green coolant problem.

green coolant vs red

What Is the Difference Between Red and Green Coolant?

Coolant comes in different colors, and there is a reason for that. It helps to distinguish the different types of coolants available better. These coolants are different in their components, stability, technology and improvement.

The most widespread confusion among car owners is the topic of green coolant vs red. Let’s go in depth.

Red radiator fluid or antifreeze

red engine coolant

Red engine coolants or antifreeze are commonly known as Dexcool®, which falls under the Hybrid Organic Acid Technology (HOAT). It lasts longer than other types of antifreeze. When you compare this antifreeze with different types like green antifreeze, it is considered more stable; this is one of the reasons it is more popularly used in modern cars. 

Green Radiator Fluid or antifreeze

The green antifreeze is considered regular or old antifreeze. It is an Inorganic Acid Technology (IAT) made using either ethylene glycol or propylene glycol.

green antifreeze

While understanding the difference between red and green antifreeze, we must know the technology in building these fluids.

We will look at three coolant technologies, including the following.

Inorganic Acid Technology (IAT)

The IAT was the first coolant introduced into the industry. Compared to other types of coolants, it has a lifespan of between 30,000 and 45,000 miles. Its short life span is owed to its properties and additives.

IAT is majorly suitable for older vehicles, as it is designed to protect iron, brass, copper and aluminum parts that could be found in older vehicles. It is why it is no longer used after the mid/late 1990s. 

Organic Acid Technology (OAT)

A new type of coolant solution replaced the IAT, which was the OAT. It uses organic acids and corrosion inhibitors, granting it a longer life span. The coolant can last up to 150,000 miles.

The downside of this coolant technology is that it does not protect copper and brass system components, making it unsuitable for older vehicles.

Hybrid Organic Acid Technology (HOAT)

The HOAT is the combination of the IAT and OAT coolant technology. It means that the coolant is suitable for both older and modern vehicles. It lasts more than the previously mentioned types of coolant technologies; It can last for up to 180,000 miles.

There are other coolant technologies, but we will only concentrate on these three for red coolant vs green.

Now that we understand the major coolant technologies, we can move on to the confusing discussion on red vs green antifreeze.

Can I Use Green Coolant Instead of Red?

No, you cannot use green coolant instead of red. However, they are designed to perform the same functions but have different components. Also, they are used for different model years of vehicles. Red coolants are designed for newer vehicle models and green for older vehicles.

Over time there has been a change in the materials used in making vehicle parts. Older vehicles tend to have more metal parts. On the other hand, newer models use aluminum, rubber and plastic parts.

After prolonged use, replacing your vehicle’s red coolant with green could damage the aluminum and rubber parts of the radiator. We can also say the same about using red coolants for older vehicles. 

Ensure the change is done on older cars, like cars made before 2000 and the red coolants for vehicles produced after 2000. If you must change the type of fluid you use for your car, contact a professional for proper recommendations. 

Can You Mix Green and Red Coolant?

Do not mix green and red coolants, it will react, and the result could be disastrous to your engine. Mixing red and green coolants will result in a thick fluid that will not flow through the cooling system when needed and cause serious damage.

When we say that HOAT, which is the red coolant, is the combination of IAT and OAT, it does not mean a physical combination. HOAT combines the effects of OAT’s rapid long life and rapid protection of IAT.

HOAT contains small amounts of silicate, borate, molybdate, or nitrate. These elements are entirely different from what could be found in OAT. OAT is made from either ethylene glycol or propylene glycol. 

The difference in the chemical components of these two fluids allows for the wrong kind of chemical reaction. A result of the mixture of fluids is a thick gel which will hinder the flow of the coolants.

If you mix the red and green coolants in your engine by mistake, do not panic. Avoid driving the vehicle and immediately invite a professional to have the problem solved.

How To Fix Problems of Mixing Green and Red Coolant?

If you mistakenly mix a red and green antifreeze in your engine, you can quickly solve that problem by flushing the mixed fluid. By flushing the coolant, you get all the mixed coolants out of the engine and reservoir before any damage can be done.

Below is an easy-to-follow step to flush your vehicle’s damaged antifreeze.

1. The first step is to park your vehicle on a safe, leveled surface. Wait a few minutes for the engine to cool down.

2. Open the fill cap on the radiator; if your vehicle has a separate reservoir for the antifreeze, do the same.

3. Locate the drain plug beneath your vehicle, place a drain pan directly under it, and then open the drain. Allow all the bad fluid to drain into the pan completely.

4. Get hold of your drain flush product and then pour it into the radiator. Try to read and follow the instructions on properly using the product.

5. Close the cap on the radiator and reservoir and start the vehicle. Leave it idle for about 10 minutes. After that, the engine shut down.

6. Drain the flush product just like you flushed the bad coolants.

7. You can now refill with the appropriate coolant. Ensure to also dispose of the bad coolant properly.


When it comes to red vs green coolant and choosing which is best for your vehicle, choosing the type of coolant recommended by the vehicle’s manufacturer. Regardless of which is better than the other, the manufacturers of your vehicle know best. You can get the best recommendation from your vehicle’s manual or a professional.

Akindayini Temiloluwa

I am Akindayini Temiloluwa, an automotive expert writer and car enthusiast. I have over three years of experience in the automotive writing niche and have completed over 300 pieces of content from 50 projects. I have vast knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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