4x4 differential fluid change??

[TrailFiend]

im going to have my fluid changed tommorow morning, but i dont know if i should use friction modifier or not. i have the g80 rear-end which calls for 80-90w. im not using synthetic oil, so i need to know if i need friction modifier or not? thanks.

[cao88c]

Friction modifiers are generally used for lockers/ limited slip diffs. If you're running an open carrier, you should not need it. Check the FSM to see if it calls for it. Also, if you use Royal purple diff fluid, it already has it.

[95CTburb19]

I think that you should put it in seeing as the G80 is a limited slip locker.

[Pete95Sierra]

yea it cant hurt to put it in i use it in my truck and i use it in all the trucks i use at work ( which are all fords :( )

[TrailFiend]

well, i put it in and it feels way better than it did before...it hadnt been changed in 116k miles!!! im so glad to have saved this truck from a bad owner. i had both diffs. and the transfer case changed. i cant wait to order my eaton e-locker and put that in, which i will then put synthetic oil in there. i got to see my g80...:rofl: what a joke! lol