2008 bmw 335xi n54 motor: Bmw recommended oil changes every 15k miles or 1 year when this car was new. I would make sure to change the oil at 7500. Webdec 17, 2014 · if you just blindly change the oil each year, all those extra changes using synthetic oil could be expensive (especially if the op uses boutique oil). Weban oil change on the average car with conventional oil may actually cost you more to diy. It may be worth it financially if you use any kind of specialty oil (including synthetic), or if. Webyour driveway is the best and cheapest place for an oil change. You don't have to be mechanically inclined or even know much about engines to do a better job than most.
