Royle Purple

As a rule I have come to accept, (after doggedly using Castrol for many years in my '70 Bonnie) that car oils are for cars, motorcycle oils are for motorcycles. The Castrol as an example has 'friction modifiers' that are wonderful for being that tiny bit more slippery than ever for the car engine parts. In the motorcycle it makes the clutch slip. I have heard a lot of good hype about Royal Purple. I might try it in my truck....
I hope this helps. (my 2 cents)