Use a borescope through the spark plug hole to look for score marks in the cylinder. A ring cannot seal properly if there are scratches that let the oil bypass the rings. Also, a worn intake valve guide and/or valve stem seals that let oil trickle down the valve stem can create pretty noticeable oil consumption and plug fouling. DO NOT let anyone convince you to install something called a "spark plug anti-fouler"- - -a spacer that moves the plug away from the combustion chamber. It also lets the plug overheat and burn the electrodes away in a hurry.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!