You have to understand that auto has a bunch of thinners and friction modifiers in it that motorcycles don't have. This is done to squeeze every bit of mpg out of an engine. Cars and Hardley's aren't unit construction, to my knowledge, so don't share the oil with the gearbox and clutch.
It's your choice to run whatever oil you want to in your bike, but the people in the know about motorcycle engines sure don't recommend it. Is you engine not worth $10/Qt, give or take a buck? That works out to be about .5 cents a mile for oil if you change it at the recommended intervals. Pretty cheap insurance if you ask me!
And for my own personal thought on it, I wouldn't put Valvoline in anything! I used to use it back in the '60. That proved to be wrong. Other oil was considerably better, so even if Valvoline has improved over the years, so has everything else!
Bare