My Corvette will be due up for a rear differential fluid change pretty soon. GM recommends it every 24 hours of track use. OEM fluid is an 75w90 GL5 LS.
I've had my eye on Renewable Lube Bio-SynXtra GL-5 LS but am not seeing many UOAs or info on here for people using it for "severe duty". It has an impressive VI (187) and their engine oils seem quite stout, so I figured their gear lubes are probably a good buy too.
Otherwise my thought was to run Motul Gear 300 LS. It worked quite well in my Audis and is also a stout formula.
2017 Chevrolet Corvette Grand Sport