losing coolant in '03 grand am
 

First time caller here.
My stepson has an '03 Grand Am with the inline 4 cylinder 2.2L engine. He called the other night and said he's losing coolant, and the oil filler cap has the familiar brown slime on the underside of the cap. I read up on all kinds of information on the V-6 engine with the lower intake manifold leaking and such, ( in fact there's a class action lawsuit going on over this) But, there is no info on the inline 4 cylinder 2.2L engine. We took the valve cover off, and took off the intake manifold too. Other than the brown slime built up around the oil filler cap area on the valve cover, everything looked fine. I suspect a leak in the head gasket. We went to Azone and bought some stop leak and dumped it in. So far it seems to be holding. This engine has the orange "dex cool" antifreeze in it. I'm suspecting this dex-cool is slowly ruining the head gasket.
Anybody else have this sort of problem with their grand am? If so, what did you find?
abe