oil in radiator overflow tank

[billinric]

We took my fiancees '99 Grand AM in for annual inspection. The manager proceeded to show us the coolant overflow tank , which had oil in it . also showed us 2 minor oil spots on the engine at each end of the intake gasket. After leaving the inspection station, I changed the oil , and it had no signs of coolant in it, and the oil level before changing it was normal. Can this be caused by a bad intake gasket ? From my limited experience , it seems that these leaks usually involve coolant getting into the oil, not the opposite . Any input anyone ?

[xeroinfinity]

Welcome to AF.

It can go many ways... Oil in the coolant, coolant in the oil(most dangerous to the engine) and coolant/oil into one oc the cylinders. Oil leaking from the ends of the block are another sign you need gaskets replaced.

My GAGT when I bought it had oil in the coolant, had to change the lower intake(LIM) gaskets to fix.
Oil in the coolant does make it less efective so you could overheat or freeze into slushy's.

After you change the LIM you'll want to do a realy good flush to your cooling system to get all that oil out.
I would suggest buying a repair manual if you plan on donig it yourself, though here is a link to the LIM procedure.
http://d-tips.com/General/Articles/Default.aspx

[GTP Dad]

Oil in the coolant is possible but not likely. There are three potential causes. Leak in the transmission cooler forcing tranny fluid in to the coolant system, bad intake gaskets or generally the primary cause Dex Cool. It will develop an oily film on the coolant in the bottle. Clean the bottle well and then recheck. If it reappears then I would keep tabs on the transmission and the engine oil. If not then it was just a Dex Cool reaction to coming into contact with air.

[xeroinfinity]

You're right GTP Dad, I totally forgot about the effects of the Dex and the lovely scum it produces.
I'd also agree with cleaning the reservoir first, and see what come back.

Though usualy you can tell by looking if it's oil or trans fluid or just Dex in the coolant. The scumy part is usualy brown/grey kinda foamy, oil brown and red if trany fluids leaked.

Hopefully, it's not that cerious.