I did some reasearch awhile back on synthetics vs traditional oils, including calling some Winston/Nextel Cup engine builders and digging up as much test data as possible and found everyone pretty much agrees synthetics are inherently better in every area, except there appears to be some question on bearing pressure capability. This is supposedly where the racing synthetics predominantly differ from the standard Walmart sold
synthetic, in that the extra additives enhance this bearing strength. The
synthetic manufacturers seem to skirt around this issue when I confronted them on phone calls (I was able to get some engineering guys at Mobil 1), even going as far as to say that the bearing strength is not a critical criteria to go by (there is a ball wear test to assess this, I recall). The obvious directly applicable anology in our engines would be, of course, the camshaft/lifter interface. I spoke with engine guys at a number of race teams, some advertising other brand oils on their cars, and was told that even though their race oils had slightly different additive packages than street stuff, it was either modified from Mobil 1 or formulated by the other manufacturers to duplicate Mobil 1 (these guys asked their identities not be revealed) - Mobil 1 is clearly the standard. Anyway, it seems to me that now that the potential bearing shortfall in the
synthetic has now been addressed with the Mobil 1 racing version, it's the clear choice to me. I've also noticed with standard street vehicles that they are more sluggish when going to a heavier
oil, so the 0w30 or 10w30 seems to be a good direction to go....