The only way to know for sure is to pick your oil and do some UOA's. See ya after your next oil change.
I agree. Test it at 2,500.....then again at 4-5k.....to see where it is. On a shared sump system, no way I would go over 5k.....and prefer 3,500.
On the other hand my BMW RT can easily go 7500 miles with a high quality synthetic because the tranny has it's own, separate sump.
I ran a 15w50 in my KTM950....and in 4,000 miles it had sheared to a high 30wt. As everyone knows....shared sump systems are really hard on oil.