How Long Can You Drive with Coolant in Oil?

Coolants and engine oil are not meant to mix together. It is one of the quickest ways to damage your engine. Both fluids consist of different components and are manufactured to achieve different objectives.

However, mistakes may happen when coolants mix with oil into your engine. We recommend taking immediate action to remedy the situation.

This guide examines how long can you drive with coolant in oil. We also discuss symptoms of having coolant in your engine oil, damages to the engine, and how to fix the issue. 

coolant mixing with oil

How long can you drive with coolant in oil?

Once you notice coolant in oil, you should avoid driving your vehicle at all costs. Engine oil is made from a different chemical component from coolants. Mixing them will cause the engine oil to lose lubricating capacity and other potent additives.

Engine oil is either petroleum-based or synthetic-based, meaning it can be obtained from petroleum or synthetic chemical compounds. On the other hand, coolants are water-based car fluids made from a mixture of ethylene glycol and water. 

Due to their different chemical components, when coolant mixing with oil,chemical components in the coolant will begin to react with that in the oil.

Furthermore, the viscosity of the oil will be affected. You will either have a reduced or increased thickness of the oil. Thus, oil pressure drops than required in your car. Once this happens, the oil will also lose its ability to lubricate the engine’s moving parts, which could lead to engine problems.

Also, if the problem is left, water and acids will form, which is dangerous to metal and plastic parts. It could damage filter plugs and also corrode metal parts.

You can expect other issues like oil balls and harmful deposits from a coolant oil mix. It is why you are expected to always check for leaks in your vehicle. You must also periodically check your car’s oil to ensure it is in good condition.

Symptoms of coolant mixing with oil

When oil and coolant mix in your vehicle due to leaks or other factors, it has dangerous symptoms. These symptoms are apparent to identify. Some of the symptoms of coolant and oil mixing in a vehicle system include the following.

1. Change in oil color

One of the first things you will notice is that your engine oil will change color. Due to the mixture of the water base and oil-based fluid, you will see that your engine oil will have a milky white or brown color. It shows that the engine oil has been seriously contaminated.

It would be best to take serious action when you notice your motor oil in this condition. Delaying will damage your engine’s components.

2. Poor engine performance

Another sign you will get from anti-freeze in oilis a drop in your engine’s power or general performance. Your engine relies heavily on the motor oil to work correctly.

The motor oil ensures that your engine’s moving parts move correctly by keeping them lubricated and reducing friction. When the oil is contaminated in the case of an antifreeze oil mixture, the oil will not be able to carry out all these functions.

Once the oil is no longer functional, your engine will experience problems like increased friction, overheating, and more. It will then lead to reduced engine performance. In extreme cases, engine failure. 

3. Engine overheating

One of the roles of the engine oil is to collect heat from the engine when circulating. It also has various ways to prevent overheating, like reducing the friction in the engine’s parts.

When oil mixes in the radiator, it will no longer be able to keep your engine cool. The engine will generate more heat due to increased friction, leading to overheating.

4. Sweet smell

Antifreeze mixed with oil will give out a quite noticeable smell. It is usually a sweet smell. The smell is significant when you open the oil reservoir or dipstick. You may also be able to smell it when driving from the exhaust system.

5. Gum up the engine

Sometimes, when your oil has been contaminated by coolant, a thick slime or sludge will be formed. It will prevent oil from flowing into the engine, which is very dangerous for your engine.

Will coolant in oil damage the engine?

Coolant in oil will damage your engine by increasing friction in its parts and causing corrosion in metal parts. Coolants contain water which is bad for your engine since a large part is made from metal parts.

Also, when coolants mix with oil, it will reduce the lubricating power of the oil. Your engine parts will struggle to move because of increased friction.

As time goes by, these parts will begin to fail, and finally, you will face engine failure.

How do you remove oil from coolant?

Now that we understand that oil mixing with coolantis dangerous, draining the engine oil is the best way to fix this problem. Once the oil is contaminated, it cannot be used again; you will need fresh new oil for your engine.

Draining the oil from your vehicle is easy and can be done by following these steps.

1. Park in your working area and leave the vehicle to cool down.

2. Get your drain pans and other necessities, like new engine oil and filter, while your vehicle cools down.

3. Locate the drain plug beneath your vehicle just before the transmission at the driver’s side.

4. The next step is to remove the drain plug. This part could be difficult. However, you can spray a penetrant on the plug before removing it.

5. Drain the oil into the pan once you remove the plug.

6. After draining all the oil, insert the plug back in place and change the oil filter.

7. Once you are done, pour in new oil and ensure you fill to the recommended capacity for your vehicle. 

Note that if you have a leak causing coolant to get to the engine oil, changing the oil will not solve the problem. You need to ensure that you find the leak and fix it immediately.


Draining your contaminated oil and changing the oil filter could be stressful and will cost you. However, dealing with engine issues caused by oil contaminated by coolants will cost more. Ensure you change the oil filter when draining your contaminated oil to avoid contaminating the new oil. 

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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