RealNeal, Thanks for your comments regarding oil and engine wear. While you've spent a lot of time(and typing) going over some of the most basic things about oil that people generally know, for the most part you stated two things - You claim that
"I'm going to postulate that there are two primary factors concerning 'excessive' engine wear, the operating temperature while operating and the amount of sulphuric acid in the oil when the engine is off and cold."
Granted you're correct in assuming that both of these factors lead to the degradation of oil, although newer synthetics like Amsoil - have strong additive packages to combat the sulphuric acid formation, especially in diesels, where blowby is more of a concern. The temperature issue you're right on. While some newer oils protect better than old at temperatures less than operating temp, the running of engines, especially hard(flogging) running when they're cold, is a major cause of engine wear/oil breakdown.
However, I think you've left out one of the single most important factors related to engine wear with oil - particle/soot content. Thats why there is such a huge buzz about bypass oil filtration(which filter your oil down to 1/10th of a micron in certain brands), and how they extend the life of your engine. As well as the preference of oils with especially good soot suspension qualities. Auto manufacturers all recognize that particles down to the size of a few microns cause engine wear - and that an OEM filter traps particles in the 20-40 micron range at an average 85% efficiency.
Also - the comment made about older folks and oil change intervals, that was me. You misunderstood the point - the point wasn't that old people were responsible for myths regarding drain intervals. The point was that people that are now older, are part of an older generation, that grew up with inferior oils to those produced today, and are therefore possibly stuck on the 'old school' philosophy that oil needs to be changed every 3000 miles.
2004 Ram 2500 Cummins HO
2000 Jetta TDI
1999 E300 (sold)