I've seen on G35 threads that it is common the valve gasket going bad and oil will end up in your sparkplug wells where the coil packs go down into. When I just changed my plugs on my 2010 G37 sedan, just now the very front right one (standing in front with the hood popped, had oil all inside around the plug when taking out the coil pack. Any info / experience with this?

 

Sparkplug boot gasket needs replacing. Do all of them along with valve cover gaskets