Previous owner changed oil every 1,000 miles with QSAD 10w40. I wasn't sure how far along miles-wise the fresh oil in the bike was when I bought it, I figured under 500 miles--as it was still clean. I went ahead and got an oil analysis on the oil for piece of mind when I changed it myself for the first time. Instead of going back with QS, I put Shell T4 Rotella 15w-40 instead. I'll do another UOA at 17K and compare to this one. So far, the Rotella seems to run just fine, but in all fairness, the QS that was in there originally didn't seem bad either. If anything, the Rotella gives slightly smoother shifting, but it could have been me since I'm a n00b rider that's learning more/getting better each time I ride.