An update, I've contacted a couple sources to try and find more information on the effect of oil Rated SM (2005 engine oil warranty requirement) that dropped the antiwear additives of Zinc from 0.110  by weight to 0.087 and phorphorous from 0.100 to 0.080 by weight on the pins and plates in the cam chain (from what i've read that is where the wear occurs in roller chains).  Shell Rotella T has 0.140 and 0.130 respectively. Seems there is some evidence of early flat bottom cam lifter (not roller lifters or followers) wear on engines using the SAE SM rated oil. Normally this is what one would find on the shelf of any automotive oil seller who is moving any inventory at all. I also wonder if we are missing some cam lobe wear for the same reason, should we be miking the cam when we have the cover off, not just doing a visual inspection?. It is still theory but I will continue until we get dead ended or an answer.  Would rather prevent the reoccurance on mine that band aid it. Max

This is dated 1999, when are they going to update it?