Oh? In that case I need to add in that I have "lunchbox" lockers (Aussie and Lockrite) and don't know if others have the same issues.

I always use Valvoline 5w30 in my Tacoma and Tundra. I put Royal Purple in the diffs and Transfer case

Yeah Junkers, same here (Aussie). Diff is set up, its going in the truck tomorrow, then over the next little bit I'll play with different types of oil and see how the locker likes it.

Castrol 10w-40

Id like to know how good the royal purple is i run castrol full syn and was thinkn bout switching. If anyone is using/used it what is ur opinion on it

one of the most important things about oil is
if you have been running a good brand for a while-- dont switch
switching is hard on your metals because
every oil has a lube and detergent "package"
and if you change the new oil trys to wash out the old oils lube package to replace it with its own

Let us know what you find out.

i run castrol GTX highmilage 20/50 in mine
and i do an oil service every 3000miles or 3 months which ever comes first

I generally run Castrol 20-50 in the spring and summer and go to Castrol 15-40 in the fall and winter.

Drove it around all day with Castrol 75W-90 synthetic all day, and the locker seems to work fine.