what does it mean when there is oil inside your antifreeze res.

i was about to put antifreeze in my car. when i took the top off the reserve, the was thick and sticky black stuff (i think is oil) on the tube. what is it?

 

blown headgasket

 

yeah....blown gasket hopefully

 

what would cause that?
its not smoking or any thing. it runs fine.

 

When was the last time you added antifreeze to the resevoir? If it was sitting for a while, all it could be is crap settling at the bottom that turned into a thick sludge. Remove the resevoir and wash it out with soap and water, let it dry, top it up with fresh antifreeze and run it. Let me know whats going on afterwards.

 

well its been a while since i've changed it.
i cleaned it last night and put fresh back in it. ill let you know in a couple days whats up.

 

Did you ever overheat it?

 

There is oil in your cylinder head. There is coolant in your engine block (water jackets). One of the jobs of the headgasket is to seal the waterjackets and keep the coolant in and everything else out. When the headgasket no longer seals, the oil can seep into the water jackets.

 

And vice versa... one way to tell also is check your oil... it'll look milky... because it's been sloshing around with the anti-freeze... remember... oil and water don't mix. LOL It's going to depend on where the break in the head gasket is... whether it has water in the oil..

 

well no, oil doesnt mix with water... but at high temperatures it emulsifies, and that is when you get the milky substance... there is a special test that you can do, but you need the right equipment... i dont remember what its called, but you run the car with the radiator cap off and use a turkey bastor looking thing to pull the air coming out through the liquid in it... if there is a problem, such as a blown head gasket, the liquid will turn blue... your mechanic should know about it....