Singhg - Thanks for that - I'll break it down a little further since I'm in the hut now with my friend Michael Collins .........
The metallic parts of the ZDDP, being the zinc and sulfur "deposit" themselves on wear surfaces under heating and actually become the "sacrificial" wearing surface for the parts. Since the deposition and wear process is pretty much continuous, the actual parts never see (much) wear. New modern car oils don't have this in them as they metallic agents that would escape the combustion chamber and get into the exhaust stream would spoil the catalyst ...... and not having the additives, in the meantime, are spoiling the bearings .....
Zippity Doo Dah Particles are your friends!
..... and YES - that WAS Hye-LARRY-us!!