Welcome to the Clinic TB!
And thanks for the kudo's on the site. I will pass that on to the others on the staff here.
20-50 is a good weight, if you go to 60, be sure you are getting multi grade. I am not sure it can be had in 60 weight, but the 20 end of the equation reduces friction when cold.
The important thing to do is not to use Automotive oil. We have wet clutches in these bikes that are lubricated by the engine oil. Normal (nearly ALL) autmotive oil has "friction modifiers" in it that will cause your clutch to slip.
Be sure you are getting straight oil, no friction modifiers. If you want to be sure, get motorcycle oil as most will not have this type of additive. Want to be double sure, look on the bottle real closely and ask the guy at the parts house.
If you want to send me your email address via our personal message system, when I get home I can see if I still have a pdf (adobe) copy of the service manual. Its a huge file to send via email, but would be good for you to have.
BTW... Might want to consider the synthetics. There are some real good ones out there.
GRAM