i've owned several motorcycles, but never an HD. i just got one, a few days ago, and have a couple maintenance questions. i watched the vids linked, on this site, but didn't find what all i was looking for. (1) how often should i change the oil? i know with a Japanese sportbike, it's not just a matter of mileage, but time as well. with my gixxer, even if it had only gone 100 miles, it was important to change the oil every six months. is a Sportster the same? what are the recommended intervals? (2) what weight oil is recommended? (3) any other requirements other than it being motorcycle rated oil? (4) how much oil, with a filter change is required to fill it? it's a 2005 Sportster 1200 custom. also, are Sportsters the "XL" models? thank quys.