Oil in the coolant

SWANY1962

MEMBER
2008 CHEVROLET UPLANDER
3.5L
V6
2WD
AUTOMATIC
17,600 MILES

Why does oil leak into the radiator reservoir?

Tuesday, June 17th, 2014 AT 8:30 PM

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Is it motor oil or trans fluid? The trans cooler is an integral part of the radiator and can leak. Make sure there is no issue with the fluid in the trans and let me know what you find.

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Tuesday, June 17th, 2014 AT 8:53 PM

CAPTAINBROCK

MEMBER
1 POST

No water in oil, does not overheat until running several minutes, however plenty of brown (not red) oil floating in water. Just had air intake manifold butterfly motor worked on by local mechanic (last week but not sure I can trust. Oil clear, transmission fluid clear

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Saturday, June 17th, 2017 AT 7:20 PM

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

Hello,

This means the oil cooler inside the radiator has gone bad and is leaking engine oil into the coolant. Here is a guide that will help you get the problem fixed.

Also see if there is an engine oil cooler by the oil filter which can leak too.

https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

and

https://www.2carpros.com/articles/how-to-replace-a-car-radiator

Please let us know what happens.

Cheers, Ken

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