Oil schedule shouldn't be a mystery, really, and I don't subscribe to any schedule....they are baselines and nothing more. Once you've lived with a bike a while it should be obvious...if you're riding the piss out of your bike and exhausting the oil, it'll show when you dump it. If it's still thick and honey colored, still smells like oil, it's not done yet. If you have any doubt (some people don't trust the visual test), send it off to Blackstone and see how it's doing after your interval. If it's still good, increase the interval. If it's shot, shorten it up. My 520 has a small capacity, and a short recommended oil change interval, 300 miles might be about right if it's dirty conditions and mostly offroad miles...or I might get 1000 out of it if I'm tooting around the street on it. Different bikes are different. Some bikes don't cool or route the oil for longevity, some bikes introduce unburnt fuel which kills oil, and they're harder on the same amount of oil than other bikes. Heat and contaminates kill oil, so if you're hot and dirty you change it more often.