75W-90 Vs 80W-90

May 08, 2004 6 Replies

My truck calls for 80W-90 gear oil for front and rear diffs. Mobil only makes Mobil1 gear oil in 75W-90 and 75W-140. Will the 75W-90 be an OK substitue?



This is for a 2000 S-10 ZR2 with the 8.5" rear axle and G80 locker...


It will work just fine. In reality it'll lubricate faster at a lower temperature.

Brian

Keep in mine that you'll still need the proper limited slip additive for the gov-lock.

Nuh-uh....

Gov-locks do not need the friction modifier additive, and more often than not, using Mobil1 gear oil precludes the need for it in posi differentials with conventional or cone type clutches.

Correct, my manual specifies that the Gov-Lock does NOT need friction modifier. Mobil 1 specifies that it's already in there, so I'm covered regardless...

good good, I thought all limited slips need the additive. I've always had open or a detroit, so I never knew.

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