hey i know a lot of guys put synthetic gear lube in rear ends to save on gas or whatever....i think i will this summer...i guess i have the same gears as you guys..i have a 91 3.1/automatic....so what kinda synthetic should i use?????

 

Any kind of synthetic oil you want... just remember it's gotta be gear oil, as in, 75w140, etc... not just engine oil. I always put the Dinosaur 80w90 in my rear axle; this spring, after I fix that 3.73/posi/disc rear and put it back under my car, I'll move to synthetic.