Two things I hadn't mentionned : master tech did an ECM flash before doing the plugs, thinking that might cure the ping. I haven't checked but this flash may be related to a TSB. It didn't help. And before I had my appointment for plugs, I ran Sea Foam, but in the gas tank not in the oil. No change.If your pinging goes away with using better premium fuel then it very well could be carbon build up on the pistons. But yes we are well into winter gas now which is a killer hell i think there is even a TSB out for poor engine performance while using winter blend gas.
If you halfway know what you are doing i would run a can of seafoam through the motor (great way to piss off your neighbors due to the smoke show it will produce lol)
Last year this happened in septembre, before winter blend.
Pretty sure gas has no impact on my problem. New plugs + oil leak into spark plug well fixed = ping gone. Tech who did the plugs thinks the oil leak could be responsible, but he's a relative rookie and had no real explanation as to how or why. Can oil on the outside of a plug cause voltage variations to the plug ?