u2slow
bilge rat
standard 80w90 , no issues ever.
Same here. I always end up changing the oil more frequently because I'm always doing things to diffs. Hate to be dumping oil I paid lots for.
I haven't ever put additive in any of my posi diffs.... except maybe a GM gov-bomb once upon a time. On worn/tired units (trac & powr-loks), the lack of modifier seems to make them grip better again. YMMV, just my personal experience.