I guess I have a pretty common problem with this engine, coolant leaking into the oil. Is there any way to tell if the cause is a head gasket vs. an intake gasket? A coolant stop-leak will usually fix the problem for up to six months or so, then it reappears. It's time to address the problem. Thanks for your help.

 

Do a coolant pressure check and a compression check of the cylinders. If the coolant test loses pressure there is probably a loss of coolant from the intake. If the coolant pressure test is good and you have a substantial difference during the compression check of the cylinders then you have a head gasket leak. Is there a white milky substance in the oil? My first impression is a leaking intake gasket. Just replaced my intake due to a leaking gasket, but it was an external leak not internal.

 

Thanks for the reply Richard. Definitely coolant in the oil, when I drained the oil it was the color of chocolate milk and the consistency of think paint.