I just tripple checked all my rear valve seals and all of them look even as seen above (blue). Its 100% not the valve cover gasket as the heads not even wet by the plug hole. Chris didn't do an actual valve job he just visually made sure they were good. At least I have another good coat of dust on the car again...lol
I would think my affected cylinder is the one that's all oily as the other plugs don't have any discolor. In the gm truck world esp. 08+ style if the plug looks white and is almost a barnacle you have a problem with rings. But those trucks have DOD and the rings sludge up and stop working from what I hear from fellow GM friends.
