Knocking in engine at start up? on 2006 Saturn Vue

My vue started to get a knock in the engine this past fall as the weather got colder. After a few minutes it stops, I guess when the oil gets up in the motor. A mechanic friend of mine suggested a sea foam fix, but it depends on the motor type. So does a 2006 Vue 4cyl (No AWD) have an over head cam or over head valve engine?
He said to try 'cleaning up' the system with the sea foam motor treatment. There was also some other thing it could be but he needs to hear it to know.

Asked by for the 2006 Saturn Vue
that is a hard one to answer without hearing it but it could be a main bearing or a weak oil pump