Originally Posted by C|3R1C
BMW has 15k as their schedule. People here (including myself) feel that this is too long even for a full synthetic because our engines rev so high. To improve longevity, I do an extra interval every 7.5k miles and I let me car warm up about 5 minutes prior to driving it. Those who track or constantly beat on their cars usually do it every 5k. It's a really simple DIY and the kit is only $160.
even some of the BMW tech and veteran tech says 15k is just insane.. testing the oil might not show, but just having to have a piece of mind I suggest changing the oil...