Gear oil for the T221 and SM465

[vectorit]

I was at Napa AP today to get more oil, you know the standard 80/95 for the Tcase/trans/axles. I saw the Royal Purple stuff, and what caught my eyes were the wt ratings 80/145 or something.

I'm interested in this stuff only because of the viscosity rating at this point.

The price was the same as the regular lube I get.

Mainly interested in this heavier weight gear oil because of the excessive heat I go through here in the summer time, since during the summer the 80/90 stuff turns to a very thin oil and everything gets louder and the Swiss watch like machined surfaces of the trans/tcase leak like a sieve.

Just wanted to hear any positive/negative comments.