I took my car back to the place that changed my oil to tell them about finding oil in my coolant reservoir. They directed me in next to a car they were working on. When I explained why I was there they both smile and took me over to the car next to mine and showed me the reservoir. It looked like someone had dumped a quart of oil into the coolant reservoir, exactly like mine did. They were flushing the cooling system and putting in new coolant. I couldn’t believe it was there for the same reason I was. They told me it’s caused by the head gasket leaking oil into the coolant and they see it a lot in 5 year old and older GM cars.

They checked my oil and coolant and said that mine was not real bad (yet) and did not see any indication of coolant in the oil. They said they seldom do, its oil leaking into the coolant system not the other way around. They topped off my coolant and oil levels and gave me a coupon for a system flush ($49.95) whenever I want it.

So, the good news is that no one dumped oil into my coolant reservoir either by mistake or on purpose. The bad news is that I have a leaking head gasket.

Anyone know if there is a good sealer for the head gasket. Would it go in the oil or the coolant?

If you have an oil cooler in the bottom of the radiator it be leaking oil into the coolant. Hal

Could be a leak or the new guy putting oil in the wrong place. Places don't go handing out free flushes when the supposedly didn't do anything wrong. Call me the skeptic. Most of those places check your other fluids when they change the oil and should have caught it then if it was a leak. Then they would have told you about it and wanted you to pay for a flush which is why it is suspicious to me.

As an aside, I went to add antifreeze to my 2606 last winter at night by yard light. Thought I had an open gallon of AF but when I started pouring, it was old waste drain oil put in an AF jug. Didn't get much and it floated on top so I overfilled it with water and AF mix until the little bit of oil flowed out. Probably still had a dab in there but oh well.

its GM, but what model & what engine?, so maybe we wont get stuck with one! thanks

My experience with oil leaking into coolant is that it will turn up as an emulsion, not as clean oil. And I have a hard time believing that much of it would end up in the reservior.

A leaking head gasket would bubble the coolant up in the radiator. This should be easily visible if you have a cap on the core. Again, you should see a lot of milky emulsion in the radiator neck. If you have some sort of intercooler, like for the transmission that could cause your problem. My main problem with any of these is the clean oil you describe in the overflow tank.

That aside, my buddy did have to change the intake plenum and mainfold twice on his 98 Bonneville. It's a wet manifold, but I forgot how the problem manifests itself. Put it this way: the local Chevy dealer had the intake parts in stock on his shelf. How many dealers do you know of that keep that stuff on hand?

Chris B.

My problem was in my 87 4.3L V6 that I bought new. 200,000 miles and runs smooth with no smoke.It still looks descent and its mainly for me and the dog to run around in.

There is a known problem with the intake gasket on mid 90"s and newer 3.1L, 3.4L and 3.8L GM V6 engines. I have had two different cars that had to have it changed. Luckily I caught it while it was leaking near the front of engine before it did damage. A lot of people have not been that lucky. NOTE: TALK NICE TO YOUR SERVICE MANAGER. THEY HAVE THE DESCRETION TO CHANGE THIS INTAKE GASKET FREE EVEN IF THE CAR IS OUT OF WARRANTEE. Otherwise it"s about a $500 job.

I think this intake gasket may be the issue I was referring to with my buddy's car. It is a 2 piece manifold, and the upper half is plastic. Maybe the leak got so far along, the manifold got warped or somehow unusable.

Chris B.

I agree that it sounds fishy that the oil change place would give a "FREE" flush coupon if they did not wrong. Unless the flush is free then they charge you for all the fluids that go back in... I also agree that when oil is mixed it is an emulsion, not just layered on top of the coolent all nice and neat. Good luck and let us know how it turns out.

Charles