gear oil weights

[comancheman]

is it alright to run 75-90 in my diffs? its just what i have in the garage already.

[Eagle]

That's what originally came from the factory.

[BLHTAZ]

Yes, that's what they should have in them.

 

Just FYI... If you have a limited slip differential, it will need a friction modifier additive with the 75-90, but if you were to run a 75-140 or 80-140 Synthetic fluid, no modifier is needed.

[comancheman]

how exactly would one findout if they have the limited slip rear end? the tags have long since rotted away.

[jared]

well you could see it once you pull off the cover, there would be little clutches and such in the carrier, but try calling a dealership and seeing if they can do a vin search and tell you what you have.

[Eagle]

Simpler is to jack up ONE rear wheel with the vehicle in neutral (not park) and the brake off & wheels chocked. Try to turn the rear tire that's off the ground. If it doesn't turn easily (or doesn't turn at all), you have limited slip. If it turns easily, either you don't have limited slip or it's already worn out.