BB’s Euromotors suggests an oil change every 5,000 miles for your BMW, Mercedes or Mini Cooper. Why? Vehicles now have small porting of interior parts and higher operating temperatures which allow for sludge to build up faster. Sludge build up can cause catastrophic engine damage. The engine below has received the factory recommended 15,000 mile oil changes which caused this amount of sludge build up at 69,000 miles. Oil really is the lifeblood of your engine. Keep your car running at its best and prevent costly repairs in the future by changing oil every 5,000 miles.