80/90 gear oil ok ?

[rmallen30]

i changed my rear diff and put 80/90 in it i guess it calls for 75/90 is it going to be ok or should i change it again we buy 80/90 in bulk so i just used it bc it was handy 2wd truck so just rear end no t case thanks matt

 

[rmallen30]

any insight ?

 

[standy]

I know the rear diff requires a synthetic gear oil, which if memory serves me correctly, I could only find in a 75/90. If its synthetic 80/90, I'd run it, but if its not, I would drain it and switch to a 75/90 full synthetic.

 

[Big Chris]

I believe there are a couple different oil speced. One is 80/90.

 

[DAVe3283]

From the Duramax Supplement to the owner's manual:

SAE 75W-90 Synthetic Axle Lubricant
(GM Part No. U.S. 12378261, in Canada 10953455)
or equivalent meeting GM Specification 9986115.

The front axle takes 80W-90, so the heavier weight probably is OK, but I would ensure you put a synthetic oil in. I believe it is required for the G80 locking differential.

 

[rmallen30]

Yes it was synthetic