I am wondering if I change out my diff oil would mobil 75-140 be good to use and do I have to add any additive to it if the mobil oil says made for lsd?
Thanks

 

Yes and no.

 

If it says made for usage in LSDs I would think that it would contain the necessary friction modifier. After you change the fluid, find a big open parking lot and do several figure 8s. If you have any gear chatter or binding you could just add in a bit of friction modifier.

* but the way everything is marketed now a days you've got to be careful. They say one thing, but it's not really what you think they mean. those tricky ba$tards. That's when you have to start reading the fine print...

 

Yep, the Mobil is fine. I have Royal Purple in both diffs on my Jeep with Vari-Lok lockers front and rear which require the additive. I found a bit of a chatter and had to do half a bottle of additive in both diffs for it to be smooth...

 

Thanks guys.

 

i think a lot of the modern full syn's have the friction modifier in it. I know Royal purple, Mobile 1, and Valvoline Sypower all state that they are designed for LSD's.

nateroach

 

Rule of thumb: If it's got the modifier in it, use just the fluid first. If it chirps on turns, add a little modifier to it just until it shuts up. As stated, I have to use 1/2 the recommended amount in my Jeep with a fluid that already has it (or at least RP with it)...