I tried mobil one synthetic gear oil, 75w-90 and it is shifting great both hot and cold. NO friction modifier just straight synthetic. I was having way too much noise in mu Torsen with dino fluid + friction modifier and when I changed it there was an immediate difference...for the better.

warmonger

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black