Rearend oil question/thoughts

[wild stroker]

Was wondering what you all thought about running 80-90w oil in our rearends versus the 75-140w?

I have ran 80-90w in most of my rear ends but saw that Ford recommends 75-140w.

Would it hurt to run the 80-90? I do a fair amount of pulling with my truck.

Just curious on your thoughts or personal experience. Thanks.

[AMSOILdealer]

I would say that is fine for the front and it depends on which rear axle you have.

[wild stroker]

I have a limited slip 4.10 rear end.

[AMSOILdealer]

Is it a Dana 70, 80 or Ford 10.25?

[wild stroker]

Sorry about that, Ford 10.25. Single rear wheel.

[AMSOILdealer]

75w140 or 80w140 synthetic required, with additive friction modifier is what I am showing for your rear.

[wild stroker]

Ok thanks, but would it hurt to run 80-90w with a friction modifier?

[AMSOILdealer]

I would use the synthetic 80w140 with the friction modifier, especially since you stated you tow often.

[m j]

I cant see it hurting anything depending on your climate.
80/90 doesnt like cold weather