I don't ride very much, but I think I am getting about 300 miles to a tank. The idiot light for the oil will go on when you get low, so it's not a huge deal. Of course keeping it full will guarantee that you never run out!!
From our wonderful Buddy 50 service manual:
ass’ part loose
I go about 1,000 miles before the light first blinks that it is time to think about refilling it. I believe that is what our dealer had said as well that at about 1000 it should need more oil. And then it is basically the whole bottle of oil that goes in.