My observations running a variety of oils are as follows:
Rotella T6 5W-40 - Works great, feels great, needs to be changed by 4000 miles. Shift feel starts to degrade slightly at 3000.
Mobile 1 4T 10W-40- Same thing as Rotella, but shift feel doesn't start to degrade until 4000, so change at 5000.
Amsoil Marine/Diesel 15W-40 - As recommended by Carpenter, feels by FAR the best when new. By 4000 it starts to feel slightly worse, change by 5000.
Castrol as used at the dealer (whatever that mystery oil is)- Seemed to work fine, wasn't able to ride long enough to find the break down point......