+1 for the Castrol syntec 75w-90. I change every other oil change. I know I don't need to, according to the manual. It comes out filthy/dirty every time.
I used to use the Amsoil in everything, now I use it in nothing. It's just too darned expensive and I found other brands that I am content with. Synthetic in the engine and rear end, seems to be a little cooler and quieter

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