My service story
My M3's differential making a strange noise on every turn, so I took it to the dealership to take a look, I been told that the differential need to add some oil in it, after 2 hours the car was ready to go and I been told it need 600 mile to break in.
Just two week later the noise came back again, at that moment the car already been drive about 700mile (I took it for a road trip), so I back to the dealership again, and talk to the service guy, he told me that 600 mile is not for 600 miles straight line mileage, it is 600 miles turning mileage. After he said this I just turn around and get in my M3 drove to another dealership for a differential check.
600 miles turning mileage for a car, I just can't not imagine