I did the 600 mile oil change, than again at 1,500, switched to synthetic at 3000 miles. I was expecting to do 5k intervals with the synthetic. I got home from work today and jumped on the bike to run errands and noticed my shifts were very clunky and the shifting into 1st from neautral was difficult again. When I got back home I checked the oil....dark black. That was at 6,600 miles. Seems strange to me, but I guess 3k it is, even with synthetic. I use mobil 1 and the bike is not a cruiser, I run her hard. How often do you guys running synthetic change your oil?