Skip the auto shop - Our mechanics make house calls

Q: Accidentally put engine oil in coolant reservoir

asked by on

Accidentally, because I was in a hurry, I put engine oil into the coolant reservoir. I went round trip out-of-town, about 600 miles. After returning home and washing my car, I washed under the hood and that’s when I realized my mistake. I immediately got all the oil and coolant from the reservoir. Should I drain the whole coolant reservoir and/or replace it? Thanks.

The coolant reservoir on your particular vehicle is a part of the pressurized system. In this case, the oil that was in the cooling system can cause a few different problems. When oil and coolant mix, they turn into a sludge like substance that can clog lines and get stuck all throughout the system. The water pump can fail due to the sludge and the various o-rings and seals can fail in the cooling system due to the oil. This problem is more serious than just draining the coolant as the whole system is contaminated with oil, which must all be removed at this point. A qualified technician, such as one from YourMechanic, will be able to asses the situation and flush your radiator fluid if necessary.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: How often should I have my steering system checked?

Just like your brakes, your steering system is an essential part to the control and safety of your vehicle. Safety is a huge concern with both of these systems since a brake failure can keep you from stopping your...

Q: Radiator hose busted

Hi there, the engine cooling system is a sealed system to prevent coolant from getting out into the environment. Coolant all over the top of the engine and steam when the engine is warm and stopped indicates a leak in...

Q: Convertible top won't work

Hello. Resetting the convertible top involves the back seats being taken out and the convertible motors being disconnected. The purpose of this is to gain access to the micro switch, which is attached to the side latch. The top must...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...