I'm with Neil V.; I have run Mobil-1 synthetic motor oil (5W50 or 15W50) since day one - along with Red Line synthetic differential gear oil.

I have run both SWEPCO's 714 (20wt) and Mercedes-Benz (OEM, synthetic) ATF, given their high temp-handling/high viscocity rating (per my tech's advice) -
no problems, yet, in the past (hard-driving) 4 years...