When do you need to change oil

First Change Oil 500kms: I followed what the manual says, I chose to do the break-in method by the book. Not much changes has happened since its only my first time to change my oil. Second Change Oil 1000kms: I replaced the Yamalube (yamaha oem oil) with the Motul Mineral 3000 20w50 and I noticed that the vibration of the bike really increased / worstened. Since I didn't know much about motorcycle I decided to use the oil a little more until I reach the 2000kms mark. Like I said I followed the manual, not knowing that changing oils every 300 or 500kms is better specially during the break in period. Third Change Oil 2000kms: Switched back to Yamalube, and had Denso Iridium iuf24 installed. All I can say is that the improvement in my Mio's performance is very noticeable. During the early morning engine preheat period, 1 push of the electric starter is already enough to let your bike run. My bike experienced its 1st ever tune up from the dealer. Fourth Change Oil 3000kms: Had my bikes oil changed again, still used Yamalube. Fifth Change Oil 4000kms: I met Maxima Oils Philippines Marketing Man, Sir Bernard Advincula here in Dagupan when he was scouting for potential distributors of his top notch Maxima Oil. At 4000kms, I already changed to Maxima Maxum 4 Extra 15w50 (I was given a sample bottle by Sir Bernard during our meet). After I changed the oil to Maxima, I noticed that my mio handling is much smoother now. and that I can reach top speed faster unlike when I was using Yamalube and Motul brand oils. I like how my motorcycle is performing now than ever. You can quote me on that. Sixth Change Oil 6000kms: Still looking for Maxim Maxum 4 Extra 15w50. I can't seem to find one in the entire Dagupan Area. I'm close to reaching 6000kms, Im already at 5867kms.

Source: http://midasproject.blogspot.com/2009/05/my-review-yamaha-mio-soul-2008-after.html