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How to Fix Coolant Mixing with Engine Oil

March 18, 2024 | Victor Lukasso

Coolant mixing up with your Engine oil doesn’t sound good since it could make the engine oil lose its viscosity. Here’s how to fix coolant mixing with engine oil and prevent future leaks.

If you ever gauged your Engine oil and noticed a milky liquid on your stick, it implies a leak somewhere that needs to be addressed.

The main reasons coolant will mix with your Engine oil are; a faulty head gasket, a broken engine Block, cracks on the oil cooler, and an overheating engine.

It would be best if you sorted out the actual reason behind the leaks before you swing into fixing it.


Also, failure to address this issue one time will lead to a fatal engine knock, probably due to the oil being unable to prevent friction.

Continue reading to see the symptoms, causes, and perfect fix to coolants mixing with engine oil.

Why Do Coolants Mix with Engine Oil?

Here are the most probable reasons why a Coolant leak will occur in your car.

1. Faulty Head Gasket

A damaged gasket head is one of the reasons why coolant will leak into your Engine oil. This can usually be identified with a cloud of white smoke from your exhaust.

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2. Blown Gasket Head

The primary function of the gasket head is to prevent coolants (antifreeze) from getting into the oil. It’s located in between the cylinder and engine Block for this task.

Any defect will cause the motor oil and coolant to mix, resulting in overheating.

3. Cracks in the Oil Cooler

This is another unique place to find a mixture of oil and coolants. The oil cooler has segments that hold the oil and coolants. Any cracks could result in the motor oil getting mixed with the antifreeze.

4. Defective Engine Block

A faulty or cracks on the engine blocks could lead to leaks; though this is almost impossible due to the strength of the engine Block, it’s still vital that you inspect it.

5. Overheating Engine

Excess heat could cause your head gasket to blow, mixing both fluids up.

How to Fix Coolant Mixing with Engine Oil?

Detecting the primary cause of an engine leak could be tedious, so I advise you to seek a mechanic’s service, except if you are grounded mechanically.

Since the first thing that comes to mind when coolant leaks into the motor oil is a faulty head gasket, then you should go ahead and inspect your gasket first.

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Followed by the oil cooler, check if your engine is overheating and cracks in the Block.

Do any of the below to Fix the problem.

1. Head Gasket Replacement

The first thing to do is check for blown head gaskets and replace them instantly. This should also address the issue of a leaky head gasket.

You can take your car to a nearby auto repair shop for removal and replacement. They will also inform you if the mixture hasn’t resulted in any issues and offer fixes.

2. Place a Steel Sealant on the Radiator

While this is a temporary fix, it works perfectly, especially when you don’t have the financial capability to get a new head gasket.

First, you’ll need to Drain and refill your coolant, then go ahead to lose the bolts holding the thermostat housing to remove the thermostat.

Next, you have to bolt the thermostat housing leaving the thermostat; this is needed to create enough space for the steel Sealant to close the leakage.

Now, you’ll need to check the spark plug coils and loosen the ones with coolant. You can also unplug the cylinder injector to avoid misfiring.

Next, pour the steel seals into the Radiator and crank the engine and let it idle for about 30 minutes (it might produce lots of Mosier due to the absence of spark plugs)

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Turn off the engine and let it cool off before repeating it 3-4 more times.

Now, please leave it to dry overnight without the spark plug in the hole; the same with the thermostat.

You can now tighten the spark plug once it’s dawn, start your engine and accelerate slowly to give the Sealant a better chance of circulating.

That’s it.

3. Run checks on your Engine Block

The last option is to check your engine for any cracks and seek your mechanic’s attention for the best fix.

How to Identify Coolant in Motor Oil?

If you notice any of the below signs on your car, you’ll need to check for mixtures in your Engine oil.

  • Constant drainage of Coolants
  • Color residue on the crankcase – brown, green, orange, and red resulting in a milky color
  • The sweet smell from the engine bay.

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Meet Victor Lukasso, the owner of V. Auto Basics. Through this blog, Victor Provides Insights on the latest tips, maintenance, repair, and techniques in the automotive world.