I used this oil in my 2011 X6M for past 4 years. I do not trust anyone with any work to my car, even a simple task of oil and filter change, do it all myself. This is the Oil I always use: M TwinPower Turbo 10W-60 Engine Oil - 1 Liter: $12.74 at ECS Tuning in Ohio,
https://www.ecstuning.com/b-genuine-...r/83212365944/ . Never had any oil-related issues with my car. Have a feeling that in your case it was just a coincidence.