How many Km should I change my oil?



Hello guys, i'm the new member of the group. I got my Duke 200 nearly a year ago and i have put a little more than 4400km on the bike, i changed the oil after the first 1000km and this is when my trouble started: the owner's manual shown that i didn't need to replace the oil until 7500km, but the service at my country's KTM dealership said you should change oil after 3500km, which is way sooner than in the manual. I live in Vietnam, with most of my riding time in hot weather and a great deal...

How many Km should I change my oil?