Q: 2003 M3 engine sounds like it's clinking and clunking
A: The proper grade of oil is important, so is having it serviced regularly at a BMW dealer. The important services are the inspections that happen about every 30,000 miles, they are important because the valves get adjusted and if they dont get adjusted they will make noise. Even under normal operation that engine is just noisy though. The minimum octane rating for all BMWs is just 91, not 95.