I haven't gone through all of this -- there is lots and lots of info to absorb here!
Two things struck me though:
(1) It turns out that the base stocks, not just the viscosity-index improver (VII), also shear. This is especially true with the advanced synthetic base stocks such as SpectraSyn Ultra™ PAO ExxonMobil makes, which have complicated molecules. They shear as much as 50%!
(2) Including an ester base stock in finished oil quadruples the Sequence IVA wear (API valvetrain wear test for gasoline engines)! This is especially scary as most Mobil 1 oils must include an ester base stock since PAO on its own is not stable. Lately they have possibly started using alkylated naphthalene instead of esters in some of their oils. The reason why esters increase wear so much is because they compete for the metal surfaces and they prevent the antiwear/extreme-pressure/friction-modifier additives from adhering to the metal surfaces.
ExxonMobil Chemical advanced synthetic base stocks
Exxon Mobil synthetic lubricant base stocks formulations guide (2017)
Two things struck me though:
(1) It turns out that the base stocks, not just the viscosity-index improver (VII), also shear. This is especially true with the advanced synthetic base stocks such as SpectraSyn Ultra™ PAO ExxonMobil makes, which have complicated molecules. They shear as much as 50%!
(2) Including an ester base stock in finished oil quadruples the Sequence IVA wear (API valvetrain wear test for gasoline engines)! This is especially scary as most Mobil 1 oils must include an ester base stock since PAO on its own is not stable. Lately they have possibly started using alkylated naphthalene instead of esters in some of their oils. The reason why esters increase wear so much is because they compete for the metal surfaces and they prevent the antiwear/extreme-pressure/friction-modifier additives from adhering to the metal surfaces.
ExxonMobil Chemical advanced synthetic base stocks
Exxon Mobil synthetic lubricant base stocks formulations guide (2017)