I'd like to change the gear oil in my front differential, but am stumped when it comes to friction modifiers. I have the D30 axle with a Richmond Lock-rite "lunchbox" locker and 4.10 gears. I've read the owner manual for the locker, and not one word is mentioned about adding a friction modifier. Yet, I have a nagging feeling that I added a friction modifier last time I changed the gear oil.....but my memory fails me (again). I'm planning to use a 90 weight oil. Can anyone chime in on this?
Related to this......in the rear I'm running a Ford 8.8 axle with (obviously) 4.10 gears. Same gear oil weight in the rear as in the front? I'd assume so, but I have a long history of making bad assumptions.