Diff Oil

[JaBradt85]

Is Mobil 1 75w90 LS fine for both front and rear diffs?

[DaveH71]

Sure is, would try to find a fluid without limited slip additive for the rear if you have a locker.

[99silveradoz71]

I used it in both, but I don't recall the LS on the label

[Ryan00TJ]

The same stuff has been in my diffs since 4k miles. Currently at 46k. Going to change every 50k from here on out.

[bossier62guy]

Sure is, would try to find a fluid without limited slip additive for the rear if you have a locker.

 

Agreed.....

[Black02Silverado]

Will work just fine. No need to find fluid that doesn't have the LS in it. I have been running AMSOIL Severe Gear in my 02 since new and now has 130k on it with no issues and the Severe Gear has LS additive in it.

[ATMINF]

If you have the G80 rear locker do not put in gear oil with a limited slip additive. I used the Mobil synthetic rear diff 75/90 fluid without the LS additive when I did my rear diff this past fall. Granted I have a 14 both 10.5 FF, so it's different than your truck, but the principle concept holds true for your rear diff.