Valvoline Synpower 75w-90

Hi fellas! I finally have a day or two to get some maintenance done and one of the projects is diffs and transfer case. I can get Valvoline Synpower thru work for $7.35 a quart. I've always run Valvoline in my other vehicles with good results and the price isn't a concern. However, it seems that very few are running Valvoline and I'm curious as to why? So, please offer up your opinions and/or experiences.

 

I should add to that, that my truck is pretty much a pavement queen. It sees very little mud and off road stuff and I tow a small aluminum fishing boat 5 or 6 times a year (I really need to fish more). So, the truck doesn't see any extreme conditions that would make me think I need 75w-140 in the rear as I have read elsewhere.

 

I run Valvoline. I have dealt with them at the OEM level. Great products great company. But I always run the factory weights. You can get full synthetic Valvoline in the heavier weight.