[bkovacs]

I used to have the same motor in my Blazer, it actually never gave me a single problem
anyways I would say if there is foam in your oil its deff. a sign that head gaskets are leaking.. just make sure you replace both instead of just one!

 

[bkovacs]

actually I take that back if those two cylinders are missing and there is foam in your oil it could be even more serious, check your heads or block for cracks