Oil on spark plugs threads

[mtopxsecret6]

Hi everyone, in the quest to fix another issue I have a thread for, ive changed the plugs again, and noticed again, that I have oil on the spark plug threads, and the plug seats on the head. There is not oil leaking down inside the plug valley and pooling, it's inside the cylinders. Ive attached some photos. I'm not getting dipstick popping out from the sump, so I'm guessing its not coming past the piston rings. Would it be coming down through the valve stem seals? 

Thanks everyone

[GTSBoy]

Compression ring failure <> oil control ring failure.

Could be ring/bore wear or valve guides.

Take it apart and find out.