I just got a new ring and pinion, plus differential in my 95 Z28 after it gave up the ghost at 133,000 plus. I got rebuilt components from Aamco, did the 500 mile break in period and have just gotten fresh oil and posi-lube. My questions are when I'm driving, it seems like the new gears are eating up some power cause it doesn't yet have the punch as before, does it need more break in time? Also what are soem of your thought on synthetic gear oil? would it be worth it to switch over to in a few miles or not?

 

Break it in good with dyno oil first.