It has a computer monitoring system on the engine and depending on how you drive, it guesses how fast the oil breaks down. But only 6k that seems like a lot. The harder you push the car the faster it tells you to change the oil. Some manuals say ever 5k or 3 months to change oil. But my personal opinion, your car calls for mobil one synthetic oil. I would not change it at the min of 7k. You can go a long time on synthetic oil cause it does not break down. The only reason you have to change it is cause it gets dirty. I have went 10k before on mobil one. I have heard that bmw owners go 17k on it.