Royal Purple HPM 80W90

[aquariuscsm]

I know this is probably the wrong forum,but I figured it'd get more exposure here,plus I was wondering if in fact this would work as a rear differential oil on a car that specs 80W90 (on a sealed rear diff that doesn't require limited slip additive). I've never heard of this lube before:

http://www.ebay.com/itm/Royal-Purple-116...a24&vxp=mtr

 

[barkingspider]

At rant price, why not go with what is proven to work and half the price like, m1 valvoline amsoil redline castrol etc. I haver seen that gear oil either and I don't have a boat