Help***Oil in coolant

I changed my coolant a couple of weekends ago. Flushed the system and ran water through a couple of times to make sure it was flushed good. I went to check the level after driving for a few days to make sure it was ok and noticed some oil floating in the overflow tank. Not much. Also looks like some oil residue in the radiator. I drive about about 800 miles a week highway if that matters.

I know just enough about cars to make me dangerous, but I don't guess that is a good thing? Anyone know what might be causing this and how bad it could be. Car has 125,000 on it.

Head gasket, cracked or warped head, cracked block. A compression check might or might not reveal the problem. I'm assuming when you say you see a little oil you're seeing a rainbow effect on the surface of the coolant. Drain the oil and check it for lighter brown streaks or any frothy, milky appearance. If yes then you confirmed you've got a problem. At that point I wouldn't drive the car except to get it to a shop. If the oil looks normal and you don't see any vapor out the tailpipe then I would flush the coolant again and keep a close eye on it.

Another way to check for a blown head gasket is to wait until the car is totally cool( overnight) then take the radiator cap off, start the car and see if bubbles come up through the coolant. If so, then the gasket is likely blown.

I changed my coolant a couple of weekends ago. Flushed the system and ran water through a couple of times to make sure it was flushed good. I went to check the level after driving for a few days to make sure it was ok and noticed some oil floating in the overflow tank. Not much. Also looks like some oil residue in the radiator. I drive about about 800 miles a week highway if that matters.

I know just enough about cars to make me dangerous, but I don't guess that is a good thing? Anyone know what might be causing this and how bad it could be. Car has 125,000 on it.


explroreco97,

Are you sure that's not residual water pump lubricricant? It can imitate crancase oil.


rimfire,22