Re: Rear Diff Solution - Is there one? HELP Please.
I might be wrong, but before you change to a different weight lube, I can tell you that five years ago guys here were reporting that inexperienced dealers were neglecting to put the anti-slip additive in the diff when they changed the fluid. The symptoms you report were similar to theirs.
Get hold of C66 Racing and get some his Amsoil Severe Gear 75W-90 in your diff. I also put a bottle of the Slip Lock additive in, but I think it already includes it. MUCH cheaper swapping out the fluid than slinging a wrench and tearing into the diff needlessly. Just my $0.02.
'05 CTS-V, Maggie, Kooks, Hotchkis, Ground Control, Corsa, B&M, DSS/Hendrix, Full 3M Clear Bra, Autovation, V Headrests, CTS Console, STS-V 55w Fogs, Black Vette FRCs, Specter Werkes, Katech LS9 Clutch, SS Brake Lines, Heavymetals U-Turn Fuel Line Eliminator, Momo Combat Evo Shift Knob, Wldwhl Clear Sidemarkers, Linea Corse LC855 Wheels, plus a couple more. Mustang dyno'd at 472 RWHP/411 RWTQ.