I have a question, I was told that my rear end takes 75w-90 rear end gear fluid. Well i changed it out, and just found out that it really takes 75w-140. Is it okay to run the other gear fluid?? I have a 9.75 rear end, supercrew, non-locking rear end, 2wd.
thanks kevin

 

I'm gonna go guessing you are putting synthetic in.... my 9.75 takes 75W140 Synthetic and then they recommend 4 oz of friction modifier too. I would drain it and start all over with the proper lube. Oh yeah just to bust your chops.... you didn't see the tag attached to one of the bolts on the cover that says use 75W140 Synthetic?

 

tag wasnt on the rear end. and I was told that only the locking rear ends need the modifier.