Transfer case and rear differential service

[Emille3]

I have a 2005 AWD with 160k miles and planning to replace the fluids in my 2005 transfer case and rear differential. I understand that the factory fluids are gm versatrac fluid. From searches, it appears that Royal Purple gear oil is ok for the rear diff in 75-90 weight. Does anyone recommend anything else or something for the transfer case? Thanks.

 

[Black02Silverado]

I would stick with the GM fluids myself. I hate it when they do this, making a fluid special to the point that there isn't much of a choice out there. I'm sure Royal Purple would be fine but if it is the only choice other than GM it kind of makes you wonder why others have not produced a replacement as well. I was surprised that AMSOIL didn't have any fluids for those applications. For as often as they need to be changed the cost for the GM fluid isn't really all the much.