Depends on oil type some break down after 1500 miles others can be good for 10k. As a tech, i recommend every 3k because Everyday drivers are used and abused hard at hot temps. The 3000 thing is not a myth or waste of money, its called proper upkeep. It's like saying you have to replace struts at 60k. May not need it but it wouldnt be a bad thing to do. End answer 3-5k intervals.