2002 Silverado diff fluid

[ShadowSS561]

I’m going to change my rear differential fluid for standard maintenance. I have a 2002 Silverado 1500 4.8L 2wd with the “GT4 G80” RPO codes. I do plan on doing a 1k mile roadtrip towing a trailer in a couple months. Should I just get whatever standard 75w90 the manual says or should I look into getting something else?

 

[Furious]

Personally for G80's aside from going for AC Delco (OEM) gear oil the only other option I would go for is Redline because their 75w90 is not only compatible with the original 80w90 part number but the superseded 75w90 part number as well which you can find on their website in OEM compatability.

 

[dnewton3]

Back then the GM diff fluid (affectionately called "grape juice" for its odor) had a spec of 9986115. Essentially it was a 75w-90 syn with some FM in it.

As long as you use a GL-5 with a friction modifier, you'll be fine. The G80 is a "locker" only in that it uses a ramp system to tighten the clutch packs to eliminate slippage. The Eaton diffs are not finicky about brand or grade.