SureTrack Community Fix: Oil And Water Do Mix

Real Fixes from the SureTrack® expert information resource are documented issues from actual shop repair orders and community discussions. Read on to see how SureTrack can help you correct issues that are not easily diagnosed using OEM information alone. SureTrack is currently available free with the purchase of a current Snap-on® diagnostic software version.

They say oil and water don’t mix, but in a radiator it mixes into a milky mess. Technicians never like to see that when opening the radiator cap since it can indicate serious damage. SureTrack community member bmaples had a Chevrolet Cruze that had been to another shop that recommended replacing the engine because of oil in the coolant. They wanted to know what the common cause was for this vehicle. They posed the question to the community, and with the help of fellow community member Richard_C and others, they were able to resolve the issue quickly.

The following Community Fix summarizes the interaction between members of the community that led to the solution.

2013 Chevrolet Cruze LS 1.8L

Engine oil in coolant, faulty oil cooler gasket.

Customer complains of engine oil getting in coolant.

Diagnostic Steps Performed/Parts Replaced
Another shop diagnosed this car as needing an engine (does have 218k miles) because there is oil in the coolant and it failed the blue fluid test. Started it up this morning and it runs fine. There’s some evidence of oil in the coolant because a bit of “milkshake” on the inside of coolant tank cap. Engine oil looks fine and I smell no strong odor of exhaust fumes inside the tank. Looked up and saw how the oil cooler is mounted behind the water outlet assembly and if it ruptured it could cause the same condition. 40 to 60 psi. vs. 15 or so psi would do that. Has anyone seen this condition or know of problems with the oil cooler rupturing and causing this condition? If it does need or the customer insists on replacing the engine or we wind up replacing the oil cooler should the radiator be replaced or can we just flush it and the rest of system out?

Best Answer from Community Member Richard_C
It’s the oil cooler gasket that goes flat. Remove the cooler and replace the sandwich gasket. Get the other O rings too and recommend a thermostat replacement as you will find that gunked up too!

Leaking Oil Cooler gasket was the cause of oil in coolant but no coolant in oil.

Correction would be replacing oil cooler gasket and complete flush of cooling system but customer is opting for a low mileage used motor against my advice.

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About the Author

Nick Taylor

Nick Taylor is the SureTrack Community Administrator and a Senior Applications Specialist at Mitchell 1 with over 25 years of experience with electronic repair data systems. Nick previously worked in the automotive dismantling and engine rebuilding industries.