I am curious what folks are using for engine oil. Are you adding anything else if at all to your oil, in an attempt to slow down metal to metal wear? I've read  lots of opinions on ZDDP Zinc additive.  We've all heard about the tappets that may suffer early wear. Or maybe the camshaft lobes are suffering accelerated wear? Perhaps its the carbon build up in the top ring and valve seats that you focus on?  Or it's the additive that helps quell your excessive oil smoke out the exhaust pipe.