Can You Reuse Coolant? The Details Antifreeze Guide

While changing your car’s coolant, you might have thought, can you reuse coolant? The question is very typical; after all, why not try to save a bit of money? But is it possible or safe to do? You might have seen others do it or want to do it yourself. Well, this article will answer your question.

reuse coolant

What Is Coolant?

Before answering your question, let’s find out what coolant is?

Zerex Coolant of the cooling system is a liquid that cools down a car. It has unique properties which allow it to go through the engine and come out of there.

When your engine is hot, you might have noticed tiny drops forming in your radiator or perhaps oil drips on the floor at the bottom of your vehicle; those are actually made by coolant entering into them from an open wound in its system.

The Function of Coolant in Cars

Before moving on, coolant and antifreeze are not the same things. Coolant forms when you mix water and antifreeze for your SUV. Antifreeze is another different substance needed for making coolant. Engine coolant is mainly a mixture of water, ethylene glycol, and dye.

The function of good coolant in vehicles is to stop your engine from overheating.

Where does coolant go? You need to pour it in your radiator with water for it to work and keep your engine operating at extreme temperatures without boiling or freezing up. That’s where it goes if you do not know it yet.

Coolant does another job for your automobile – it lubricates your automotive components and prevents damage to the engine, piston timing, water pump, head gasket, and cylinder.

Signs That Your Car Needs Coolant

  • Steam or the smell of boiling maple syrup is coming from your car.
  • Pieces of dust are visible in the antifreeze.
  • Orange or green fluid leaks out under your car’s hood (that is the color of the antifreeze). The color could be pink, red, purple, yellow, or blue.
  • You can hear a grinding noise coming from under your vehicle’s hood.
  • The temperature gauge gives a reading hotter than normal when you start the engine.

Can You Reuse Coolant?

The idea of reusing old coolant might sound heavenly to anyone who wants to save some extra bucks. So, the question, can you reuse antifreeze does not have a short answer. You can reuse engine coolant, but with some steps.

To reuse coolant in Denso Radiator of your vehicles, you will have to strain it off any particles by using the coolant strainer. Old coolant is full of materials harmful to your car’s engine – such as rust particles, so you will have to clean the coolant catch pan before draining it. If not done correctly, parts of your car the coolant comes in contact with will be clogged or suffer from build-ups which thus will make your vehicle’s engine heat up and cause damage.

To avoid this, you need to filter it thoroughly before putting it back.

But beware of reusing coolant back that has already surpassed its life expectancy. Now you might ask, does coolant expire?

Coolant that has still not been opened does not have an expiry date; it has an indefinite shelf life, but the coolant in the radiator does have an expiry date. The expiry date is written in the coolant’s container, so definitely check it before using it again. You really wouldn’t want to damage your vehicle by trying to save a few bucks.

Most people will still recommend you to buy a new coolant because the damage (if not filtered correctly) will cost more than the little money you will save by not buying another one.

What Happens If You Mix Old and New Coolant?

You can mix new and old coolants and be perfectly fine, as long as they are both of the same colors and the old coolant has not expired. Even if they are of different brands, the formula is the same if they are the same in colors.

However, you should not mix two different colors. Different colors have different formulas. Their essential components are the same – such as glycol, but additives differ.

Now, if you wonder what happens in mixing? For example, you have an orange and a green coolant, you will end up with a thick jelly-like mix and then clog your system, leading to overheating your engine, thus damaging your automobile.

If you don’t know what type of coolant has been used before, flush the old coolant entirely from the system before adding the new one to avoid any damage.

What to Do with Old Coolant

Coolant is very dangerous to humans and animals alike. Therefore, take your old antifreeze to a recycling center, service station, or auto-parts shop.

How Long Does Engine Coolant Last?

On average, coolant lasts two years. You should change your first coolant after 210,000 km (140,000 miles). After that, you can change your coolant every 30,000 miles (48280.32 miles).

You can determine if your coolant won’t last anymore by bad coolant color. Coolants are transparent when fresh, but the coolant color will be more brownish and opaquer or sludge brown when expired and coolant smell will also change.


1. Can You Drain and Reuse Antifreeze?

Yes, you can if you strain the antifreeze properly and get rid of rust and other harmful particles. If you keep those harmful particles, such as rust, it will damage your car’s engine. We recommend not to reuse coolant if you have budget.

2. Can You Add New Coolant to Old Coolant?

If the old and new coolants are of the same color, the answer is yes. Don’t mix them if they are of two different colors.

Using coolant

3. Does Coolant Really Need to be Changed?

Yes, because coolant has a life expectancy like other products, and once it exceeds that, you should change it. Typically, you should change it after 30,000 miles.

4. How Do You Reuse Coolant Filter?

Changing coolant filters after 100,000 miles or what the manual says is better to prevent future problems.


Hopefully, this article answers the question of “can you reuse coolant?” and other inquiries and questions you might have had. You can indeed reuse coolant, but with some steps it is always best to buy another one to avoid paying thousands in the future by trying to save just some dollars.


Shafiqule Islam is a graduated Mechanical Engineer. He has both on hand and managerial job experience of 15 years in automobile maintenance field. He served as Captain in Electrical and Mechanical Engineering Corp of Army, Technical Head in Taxi Cab business, Head of Plant in Car assembly plant. He is writing automotive contents to share his expertise knowledge to car lovers for solving their vehicle issues.

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