I have ran GTX 40 wt for years in my 4 stroke quads, heck I change the oil about every 3 to 4 weekend trips and these bikes have ran for years with no problems, heck ill blow your mind, I have been running Transmission fluid in my crank case on my 2 strokes for over 18 years and no problems either!
The way I see it your gonna change your oil out wayyyyyy before the oil ever breaks down, so your more or less just putting in clean oil which is great!!!!! No cantaminants (Blow By, Clutch fibers, Dirt, metal wear, ect) if you feel better using the good high dollar stuff go for it.

 

Yea no clutch I don't see why not...