mayarmar & Ymsin posted results of used oil analysis. The metals analyzed are possible wear metals but what about the additive metals depletion as they are used up? I did not see a reading for zinc, calcium, or magnesium. The very low reading of phsphorous does not make sense to me unless they stopped using that additive. Another important element for additive/wear/condition is sulfur but there was no reading for it. Also there was no mention of viscosity or viscosity index. But synthetics should have very good VI.
I also use Mobil1 10W30 change every 7500 mi as specified in manual. I should take interval oil metals readings as miles gets accumulated. You peaked my curiousity.
BTW I work for a major oil co. and have a 92 400e with 166k mi.