Re: 11,000 rpm bike motor vs a 6800-9000rpm NASCAR motor...I would think that engine design of the bike motor puts no more stress on itself than a NASCAR engine. Probably less. I would suspect that a NASCAR motor sees more load on it during a race pushing a 3400 lb. (?) car+ driver around than a High reving bike motor pushing 650 lbs. (with driver?) around.
Gearing and wind resisistance probably should be taken into account. My point being, i believe a NASCAR motor puts great demands on an oil. BUT...what do I know...