Mobil 1 75W 90 LS

[Kpwweb]

I’ve had Amsoil 75w90 in the rear axle-G80-without LS additive for the last 65000 miles. No issues.

 

[SuperOldSchool]

Don’t overthink it and change it. Mobil1 is great. I used Amsoil. Here’s my results at 39k change. Clean fluid is better than old/ dirty fluid...

https://www.tahoeyukonforum.com/thr...nsfer-case-fluid-early-on.94453/#post-1128531

 

[UFBeef]

I put 75w 90 Amsoil in both front and rear, 15 z71, no issues so far. Amsoil states that the 75w 90 is acceptable replacement for GMs goofy made up oil in the front diff.