I've not heard of any differential failure due to "bad" gear oil brand. Whatever is approved by SAE is OK.

But I personally use full-synthetic RedLine fluids everywhere around the car. I only use Mobil1 (as a cheap solution <img src="/forums/images/graemlins/smile.gif" alt="" /> ) as the engine oil, everything else is RedLine.

Oleg
Axiom 4WD 2004: OME shocks, 32" BFG Mudders, RockSliderz, OME929+2" spacers, Stinkyfab bent RE rear links, front ARB locker, rear No-Slip locker, DOR front axle lowering kit, custom middle section skid plate, IronMan torsion bars.
Deceased Rodeo'02 4WD.