Oil in Coolant Reservoir: Causes and Troubleshooting

Just like a human body, your car needs a regular checkup. It helps you to diagnose any problem at the earliest possible hour. One common car engine-related problem is oil in coolant reservoir. If not fixed at the primary stage, it can damage the whole engine.

Whether you are currently facing this problem or not, it is better to know the symptoms and causes of oil leaking into coolant along with some probable solutions.

What Does Oil in Coolant Look Like?

Oil and coolant are two different substances, stored in separate parts of a vehicle. The oil minimizes the friction between the internal car parts. The coolant or the cooling agent controls the temperature of the engine. These two things should never get mixed. If they do, your car is going to face some serious troubles.

The most common sign of oil in cooling system is the presence of a slimy milky-brown layer in the coolant. There might be an oily sheen on top of the liquid at the early stage of contamination.

oil in anti freeze
Coolant looks like milky brown when oil gets into the reservoir. Source: The-Drive

Let’s move into the reasons why there is oil in coolant reservoir.

Reasons for Oil Leaking into Coolant

Several components could be responsible for oil in anti freeze.

Damaged Head Gasket

A broken or damaged head gasket is the prime cause of oil getting in the coolant. You can find this head gasket beside the engine block. It maintains the proper level of air pressure and prevents the engine oil from leaking. However, an overheated engine can blow this head gasket, which results in oil leakage in the coolant reservoir.

Faulty Oil Cooler

A cracked oil cooler is a common reason for oil leakage. Nowadays, most cars have attached oil coolers, which can get cracked over time or because of overuse. If there is oil in your car cooler, check if the oil cooler has any crack. If yes, replace it as soon as possible. It doesn’t cost much, so you don’t have to worry about the expenses.

Cracks in the Engine Block

If you find oil mixing in the coolant reservoir, examine the engine block and look for any cracks. Lack of sufficient oiling and cooling when the engine gets heated, cracks can appear.

An engine block crack is bad news because you have to replace the whole engine. It’s an expensive repair, costing around $5,000.

Defective Cylinder Heads

Due to the extreme heat generated by the engine, the cylinders and cylinder heads may develop cracks in different places. These cracks let the oil leak and contaminate the coolant.

Changing the entire cylinder is necessary if there is any crack on the cylinder heads. Repair costs will vary depending on the car model.


Oil in Coolant Reservoir: How Dangerous Can It be?

In a nutshell, it is not safe for the oil and the coolant to get mixed. These substances are composed of different elements and serve completely different purposes.

The function of oil is to lubricate the whole engine with its thick consistency. Contrarily, the coolant has water-like consistency and prevents overheating of the car engine by keeping its temperature low.

Once the coolant gets contaminated by the leaking oil, it cannot keep the engine cool. And an overheated engine can create various problems, leading to expensive repairs.

Solutions for Oil Mixed with Coolant

Oil in radiator fluid means you will face several problems when driving the car. Engine overheating will be a common issue and smoke can come out from under the hood in severe cases. There could also be issues like a clogged radiator, failure of the radiator, and faulty temperature sensor.

What to do? Keep calm, and unless you are a car engine expert, immediately call an experienced mechanic.
The mechanic will inspect your car engine thoroughly and suggest a repair plan. A professional diagnosis is the only way to find out the root causes of this problem and fix them.

oil in cooling system
Ask for professional help. Source: Cash Cars Buyer

Troubleshooting may involve flushing out the contaminated coolant and topping up the reservoir with fresh liquid. Nevertheless, be prepared for any situation as you may need to change the whole engine in case if this problem is persisting for a long time. It is better if you can find someone who has experience in dealing with this problem before.

Wrapping Up

Oil in coolant reservoir can cause severe problems to your car and put its efficiency at risk. Identifying the cause at the initial stage will save both time and money. Hence, we suggest that you keep a sharp eye on your car’s performance and do its checkup regularly. Whenever you can identify trouble, contact a professional mechanic to have a look at your engine.