I have searched many threads, but have yet to find one that gives me the answer I really want. I think I know, but want to make sure that when I change the front differential gear oil, that I do not need the friction modifier, correct?

Also, which gear oil do you think I should use, 80W-90, 75W-90, 75W-140 or 85W-140? AdvanceAuto lists several grades, but I am not sure if it makes a difference, or not.

Thanks in advance for any suggestions!

 

80w-90 will do just fine, 3.6 pt. And stock front diff wont be L.S so you don't need friction modifier.

 

Thanks! that is what I was thinking, but wanted to be sure before I bought the supplies.

 

I think the 75w-140 is for a 4.10:1 ratio so unless you have that then use the 75

 

Both my diffs are factory ls. I would check your axle codes first

 

I used 75-140 btw

 

I know my rear is LS and I am pretty sure the front is not.
What axle code for the front would tell me I have LS?

 

I think they all have their strong suits, im just going by the chart i have, and yes check your door sticker first.

 

When I did my rear diff last year, I used 75W-90 Valvoline and also the friction modifier.

 

What axle code for the front would tell me I have LS?
Would it be the same as the rear axle code?