Car is a H/C Z 16K miles. 500 miles on it since all work was done. Drove it Friday night, got up Saturday morning, was colder here than it had been Friday night. Well I went to check the oil, just because, no real reason, and it looked to have a creamy, chocolate milky appearance to it on the top portion of the dipstick, just above the "full mark".

So I immediatly freaked and thought the head gasket was leaking (I was **** about cleaning the deck surface, all bolt holes and then wiping everything down with rubbing alcohol. Brand new head gaskets from GM. Everything torqued to spec. So I didn't see how the hell the head gasket was leaking. Anyways, I went to Autozone and rented a coolant system pressure tester came home and hooked it up. Put 15.5 psi on the system and let it sit overnight. A total of about 12 hours. I noticed that it dropped down to about 15 psi within the first few hours and then the next day when it warmed up it rose back up to about 15.25 psi. Never dropped below 15. This seem normal?

Also did a compression check. Numbers are a little lower than normal because I'm running the MS4 so I'm sure I'm losing some cranking compression because of that.

All cylinders were between 181-184 psi.

I've seen a creamy substance under the oil fill cap before, and know that condensation usually causes it, can it also form in the oil dipstick tube?