I use synthetic oil but i will tell you how to use oil for an used bike Okay, The CRANKCASE holds about 2.3 or whatever the label on the side says. But the first time you start the bike after changing the oil, it will have to fill from the oil pump, through the filter, and up into the engine.
After filling the oil until it reads in the range on the sight glass (WITH THE BIKE SITTING LEVEL, NOT ON THE KICKSTAND!!) start the bike and let it run for about 10 seconds or until the oil light in the dash goes out plus about 5 seconds, whichever takes longer. Then, let it settle for about 30 seconds and check your sight glass again. My experience (K6 Gix six) is that if will take somewhere on the order of 2.6-2.8 qts to fill to the top of the ideal range after priming the oil system.
One more thing: if you run the bike for more than about 30 seconds and the oil light hasn't gone out, shut it off immediately and figure out what you forgot to tighten. It shouldn't be hard. There will be a big puddle under the bike. Custom Parts For Mercedes