I know water gets into the oil from a blown head gasket, but how can my oil get into my coolant? There is no water at all in my oil. I looked in my coolant, though, and it was oil colored sludge. What causes that? I hope it's nothing too bad. At least there shouldn't be any internal damage, since lubrication was not affected. Still, it obviously needs to be fixed immediately, if not sooner.
Any help? Thanks.

 

Could it be tranny fluid?
I had a tranny cooler in the radiator go and began seeping into the coolant, I didn't realize what it was till it REALLY went and made a huge mess. If the coolant manages to get back into the tranny it will blow a tranny faster than coolant in oil will a motor. Only thing that saved mine was as soon as I knew what happened I pulled the coolant cap being careful not to get burned by coolant splash. This is important beause while running the tranny lines can have more pressure than the coolant but upon shutdown tranny lines have zero pressure while the coolant is pressurized till it cools.

 

Could be a couple of things. Could be your radiator is old and full of stuff. Could be a blown headgasket (when I had oil in my coolant it was from a blown head gasket. It also bubled with the cap off, alot). You could always pressureize the radiator and see if it hold psi. Also a compression test couldnt hurt.

 

Doesn't mixing Dexcool (orange) antifreeze, and regular (green) antifreeze result in brown sludge?

Have you mixed antifreezes?

 

I think someone mixed mine in my 97 cause its a bit brownish. But it runs fine. Just havent changed it yet.

 

When the colors get mixed, does it just turn brown or does it get all thick and slimy looking with a somewhat mottled appearance?
I drained it tonight and filled it with straight water I can look at it tomorrow to see if anything has leaked in the coolant. Tomorrow, I'll probably flush the system and fill it properly.

 

pour some in a clear glass let it sit for a day or so and if its oil it will seperate

 

Before then, had you ever changed your coolant?

 

Take the radiator cap off and start the car and if the coolant has bubbles coming up the your head gasket is blown.

 

if it is oil, on these, it is from a failed trans cooler(in rad.) or a fail oil cooler(on engine)

I can't remember seeing oil in the coolant from a headbasket, unless you had a major bubbling coolant issue