Is Mobil 1 75-90 Gear Fluid Recommended

[BNAZ]

1 Have About 500 Miles On New 3:55 Gears. I Bought Mobil 1 75-90
And Another 4 Oz Of Friction Mod. Is This Gear Fluid Good Or
Should I Find The 75-140.

 

[HISSIN50]

The 75W-90 is closer to the weight that is 'recommended' per the service manual. I would think that weight should be fine, and it will do you a little better in the winter than the thicker stuff, IMHO.

Good luck.

 

[BNAZ]

Thats what I thought. I was concerned about using synthetic cause its a 90 w/135k but I replaced clutches and seals with new gears.
Thanks

 

[Shakerhood]

I am pretty sure 80W-90 is what is called for in the rear end.

 

[89MustangGX]

I recently heard that Mobil-1 may now include the friction modifier. Might want to check out their website or go over the bottle closely to find out if you still need to add it.

 

[8950HO]

I`ve been using Mobil 1 75w90 gear oil since the early 90`s in my 89, 5.0L without the Ford friction modifier,(I don`t think it`s necessary with this gear oil),without any problems to date,not even a leak.

 

[HISSIN50]

FWIW, next change I will be running straight 75 or 80W-140. The charts on Redline's site are kind of interesting. IIRC, the syn 75/80W-140 flows BETTER than dino 75-90, so WHY not.
It is very very hot where I live - I might not do this in a climate where the stang is driven in temps below 50*F or so (I did not read the charts with concerns for cold temps).

But for you warmer climate guys, something to consider.......