royal purple 75w90 or 75w140 or is there a better brand and option I know this has been covered before but i'm at work right now and don't have alot of time to search

on AM the 75w140 says recommended for S197s so I'm leaning toward the 75w90


Opinions please


going for 4.10s btw

 

Not sure what the 7.5" needs but the 8.8 used either 80W-90 or 75W-140. My manual for my GT says the latter and since the latter is slightly less viscous, it may be better for mileage sake.

 

75w90

 

Bump


any of you guys with 3.73 or 4.10 in you sixers what do you run in the rear diff