Ive changed my oil about one month ago but just recently my check oil light has started coming on and I started losing my heat. I thought I might just have low antifreeze but when I opened my radiator cap I found a giant glob of brown mud clogged up under the cap. I scooped it out and it feels thick but has an oily texture. There is still a lot left in my cooling system. I know Dexcool coolant is capable of this but with my unrealistic drop in my oil I was wondering it it could be a head gasket or intake gasket leak? I had just done a complete flush of my cooling system about 7 to 8 months ago as well.

  • 2
    Head gasket is bad.
    – Watsche
    Oct 10, 2014 at 7:40

2 Answers 2


By far the most likely cause for this is, as you guessed, a head gasket leak, allowing oil to leak through to the cooling system.

This often happens not long before complete failure of the head gasket and potentially major damage to the engine, so get it to a garage now for a new gasket, radiator flush, check on rad pump etc.


DexCool anti-freeze turns to a brown clay-like sludge after a while.

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In 2008 a class-action lawsuit with GM was settled over DexCool.

Here's a nice video showing the resulting mud stuck in the system.

Some common suggestions to help flush it (rather than having to replace the radiator and engine) is adding a bit of dishwashing detergent to your radiator and driving around for a few days.

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