What motor oil do you suggest?

Boy this question is opening a can of worms!! But I like it.

In the race car (440 Duster) I run 15w-40 Rotella, the others I run Castrol synthetic! 5W50 for the turbo Shadow (248 hp at the wheels) and the truck. The rest of the fleet gets Castrol synthetic 5W30. I buy the Castrol at Costco and all oil changes are done by ME!
:cheers: