I am changing out my front and rear differential fluids as well as the transfer case.
My brother in law has 10 quarts of new Mobil 1 synthetic 75-90 oil he said I can have, but I see that the manual calls for 80-90 in the rear diff.
Is there and danger in using the 75-90 for everything?
Thanks

 

No. As long as it meets the GL5 spec, it will be fine. Should say so on the bottle.

 

its all the same. I am using 75-90 in my f/r diffs, tranny and tcase.

 

Awesome thanks for the help .

 

Dont you need to add friction modifyer if its l/s?

 

no you dont.. if you wheel a lot or pull anything a lot you should bump that up to 75w110 or 75w140. much better protection. the newer 90wts are thinner than previous mixes for some reason. even amsoil tells you to bump up in weight

 

No I dont wheel alot. My wife drives this 90% of the time on the streets.
I do take it up on the mountain roads/puddles every now and then just to get dirty and shoot guns at stumps.