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 1,000 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
  1. Home
  2. Questions
  3. Accidentally put engine oil in coolant reservoir

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: 1998 Pontiac Bonneville leaking oil

An external oil leak is generally caused by a leaking seal and typically not a cracked piston, while a cracked piston is not completely uncommon, it generally doesn't cause an oil leak unless it has come apart and popped a...

Q: coolant replacement

Hello. The radiator cap for your particular vehicle can be purchased a part store like Advanced Auto or AutoZone. The radiator cap should cost about 8 to 15 dollars. The Duralast and Dorman radiator cap listed at AutoZone should fit...

Q: Antifreeze emptying out fast

Hello. If this happened right after the work was done, then it is typically caused by a hose that is loose or the thermostat not being installed right. If you cannot see the leak, then the system will need to...

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...
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...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...