today i am rebuilding my rear and i bought 75w90 lucas synthetic gear oir for it my question is shoul i have gone 75w140 because my brother when he did his rear the 75w90 was to light and his rear got really hot so should i be fine with what i have or get the 140

 

Spec is 80w90 (75w90 is fine). I would be more questioning the setup of the diff if it got hot...

 

well his manual says 75w90 for normal driving and 75w140 for harsh conditions and we wheel so that is why i was just wondering and at the time he jsut rebuilt he whole rear ring, pinion,bearings, and a lsd i am jsut replacing the carrier with a lsd and new bearings that go on the outside of the carrier so would his heat be due to the new ring and pinion??

 

What manual are you reading from? Owners manual states 80w90 with no mention of 75w140... Factory fill was 80w90 for both front and rear (GM PN 1052271).

Still don't see a need to go to a 140 weight oil even for offroading... But whatever floats your boat.

 

ok thank you and i was refering to my brother about him reading about the weight but thanks for your help i was just wondering before i went and did it