IMO, I feel to change your oil twice before the service is due. I change it every 4k... I know sounds crazy but I do this because one day my mechanic showed me a BMW 540 2000 model. The guy had the car towed in because his engine stooped working. The reason was because the engine needed a complete overhaul. I'm looking for the pics to show everyone how nasty it looked. This guy bought the car brand new. Changed the oil every time the service was due. Never let it go past the service time. Because of this the engine had build up so much gunk inside, it looked like actual "Fat" that our body stores. From that point on, my mechanic said not to listen to BMW and do a few oil changes before its due for the service. Now everyone has there opinion. But if you think about it. Synthetic oil breaks down just as regular oil does. Better to be safe then sorry. If you are planing on keeping your car for a long time, then take care of it. If you plan on just leasing or keeping for a small time then who cares. But the next dude might get a surprise later on. This is just my opinion. I'm looking for the pics, once I get them I will post them... Hope this helped...