can i use 10w20 or 10w30 in the tranny?

As to actual "weight" doesn't matter much.
As long as it doesn't have friction modifiers, says "energy efficient" "high milage".

It should say "wet clutch compatible"

I don't know the "rating" of the oils.
Either get motor cycle or atv oil to be safe. Or ATF.
 
Yes you can run 10w30 or 10w40 if you would like. Just keep an eye on it as you may need to change it more often. If you can find 'type F ATF" transmission fluid then that is what I prefer to run.