i am changing the fr/r diff fluid trans (man) and transfer case. i put 75w90 in the frt axle instead of 80w90 i'm using royal purple and this crap is exspensive. do i need to swap it out and get the 80w90? i didnt see any royal purple 80w90 gear oil. the truck is in the garage right now waiting for me to make up my mind. can anyone get me quick answer?

 

I've been using Amsoil Series 2000 75W/90 in front/rear diff, transfer case, & manual tranny for 6 years now. Shifts so much smoother - especially when the temp drops. Never a problem - yet. Don't worry - just keep feeding the runner the good fluids and they'll run forever.

Andrew

 

yeah i'ma keep the 75w90 in there, hope it works out okay i'm sure it will. the 96 takes a couple different fluids than the 94. my manual says i should use dexcron atf II in the transfer case and 80w90 in the diff and 75w90 or 80w90 in the tranny , although i am positive anything is better than what was in there.

 

With gear lubes, the 2nd number (hot viscosity) is the most important. With xxW90, really makes no difference what the "xx" is, that is just the cold viscosity. Once the diff is up to temp, 75W90 is the same as 80W90 or even straight 90W.