1995 Chevy 3/4 ton 4x4 I`m in Canada so it gets down to -38'C here and already use PP syn for the engine but would like to change Diff`s and Tansfer case to Synthetic oil. Recommendations would be appreciated.
I would recommend Petro-Canada Traxon synthetic in my diffs. According to manual its says to use ATF, so I use Petro-Canada DexronVI (supplies GM as OEM ATF) Available at any Petro-Canada bulk dealer, very good specs (-51C pour point)as well. I use it in my 1997 Suburban and its excellent:
Royal Purple MaxGear for the diff's( in the appropriate weights - use 75W-90 in place of 80W-90 if called for ). I would assume your t-cse would call for Dex ATF so Royal Purple MaxTF there.
Redline is a very good brand. Their gear oils and ATF's are some of the best out there. They are pretty much my 2nd choice for fluids other than oil behind RP. If it is more readily available to you than the RP it is an excellent company with great fluids. It is more $$$ than RP however and harder to come by for me anyway.
I have a 94 k1500 14 bolt rear end 9.5" ring and pinion gear and have the same question. I can get a pretty good deal at Summit racing on the 75W 90 Synthetic. Does anyone have experience with this oil?