Amsoil Dominator and castor 927 both great stuff ! But 927 is a good bit more expensive and it was actually too thick for my likings so I would go with Amsoil if I were you. 

Amsoil Dominator and castor 927 both great stuff ! But 927 is a good bit more expensive and it was actually too thick for my likings so I would go with Amsoil if I were you. 

It really does not matter what we think about the thickness of the oil.  What does your engine think about the thinner oil???