Pontiac Repair: 2002 GP 3.8-NA coolant & oil mixing, radiator hoses, upper intake manifold

Question
Hey Todd.

My 2002 GP 3.8 has trace evidence of oil in the coolant and coolant in the oil.  I observe this by checking the rad-cap and oil-fill cap. (The 2 highest points in each system)
I don't think it's a head gasket--engine runs fine.

I can't see any evidence of leakage outside the engine.

I've heard that the plastic intake manifolds are prone to leakage. (Another quality innovation by GM)

Would this cause minor seepage of oil and coolant?  Are there any other things to check before replacing the manifold?

The manifold looks easy enough to replace.  Any recommendation before I start?

Thanks again...
Colin

Answer
Hi Colin:

these don;t have head gasket issues. and it's hard to get oil into the cooling system. what you may have going on is a few things transmission fluid could be laking from the cooler into the cooling system or I have seen radiator hoses start to break down and the oils in the rubber start to look like motor oil. the big issue with these engines is the lower intake manifold gaskets and the upper intake manifold it's self. the GM replacement lower intake gaskets are made of aluminum and they do not go bad anymore. as for the upper manifold you can look around on the net for an aftermarket one they have ones that state that they have an improved design around the EGR pipe so they don't warp or so they say. the upper intakes is really not all that expensive from GM but it's the exact same part your taking off your putting back on.  good luck :-}