Motorcycles are heck on motor oil. The clutch puts the oil through tremendous shear forces and chews it up fast.
Always change your oil out after every other ride or so, no matter how hard the ride was.
More than likely, the clutch plates needs to be replaced. I would change out the basket as well while there. More than likely notched.
Once you know the clutch is in good working order, try to use something other than the XXw30 fluid. I would suggest using Type F ATF. You will hear some disagreement on this, but I have alot of faith in type F atf, as it is loaded with barrier additives and is a very thin bodied fluid.
Type F (don't mistake this with other types of ATF) works in a different way than Dexron/Mercon typoe ATF's do...Type F has a dynamic coefficient of friction that is reduced when the revs are high, which is exactly opposite of how Dexron/Mercon type fluids work.
I know that this would seem to be the opposite of what you need from what you have described...but I feel you have a mechanical clutch problem that first needs to be addressed before you will have any idea of what fluid really works best for that bike.
All that said...even if you do use a xxW30 motor oil, the bike should not do what it is doing. Heck even if you are using a 50wt oil in the middle of winter, it shouldn't do that...well maybe a little.