Couple Of Differential Fluid Change Questions

[OL_FAITHFUL]

Getting some mileage on my truck so figured I'd change the front and rear differential fluid. Book says 80W-90 for the front diff and 75W-90 Synthetic for the rear. Are there any special additives to add to front or rear diffs along with the fluid? Does the rear axle have a drain plug, or will I have to take off the cover (haven't ever looked closely)?

 

Thanks

[MS3DALE]

No special additives needed or required.

No drain plug on your truck (the 8.625" rear axle does not have one)

[05GMCZ71]

never use any type of additives in the rear diff if you have the G-80 rear locking diff. As for the front, I am not sure.

[Black02Silverado]

You can run 75w-90 in the front as well. No need to have two different bottles of gear oil on the shelf.

[Z45]

Front Axle (1500 Series) ? Four?Wheel Drive

SAE 80W-90 Axle Lubricant

(GM Part No. U.S. 89021671,

in Canada 89021672).

 

 

Front Axle

(1500, 2500 HD, and 3500 HD Series)

SAE 75W-90 Synthetic Axle Lubricant

(GM Part No. U.S. 89021677,

in Canada 89021678) meeting

GM Specification 9986115.

[jwhjr]

75-90 in both and you'll be fine.