oiled spark plug

[Bob Culver]

There seems to be some confusion. Externally stepped rings are fitted step down (incidentally such rings have a much increased gas leakage path) Slightly taper face rings are fitted small external dia up as per many sources. At moderate miles such rings show wear at the bottom only. The ring rides the oil film on the up stroke. (A common somewhat desperate practice was to file or oilstone a very slight bevel on the top edge of rectangular rings.
Is the plug oiling and causing misfire or vice versa?
I dunno if any anomoly with the oil jet would affect just one cylinder