2008-2013 BMW M3 E90/E92/E93 Maintenance and Cost
It's important to remember that, although the E9X BMW M3 is based on the normal 3 Series, its maintenance will be rather more expensive than that of its lesser siblings - that is an unfortunate reality of employing a highly-strung engine in a road car. These issues usually only show up at higher mileages, though, and an M3 should otherwise prove fairly reliable as long as the OEM maintenance requirements are met.
Owners could expect to deal with the usual BMW quirks as an M3 ages, such as oil leaks from plastic valve covers and VANOS solenoids giving up the ghost, as well as M-specific issues like premature connecting rod bearing wear. But, in the latter case, most M-car owners have accepted that rod-bearing replacement should be considered a maintenance job, rather than an actual design shortcoming.
BMW uses a system called "Condition-Based Servicing" (CBS) for the on-board computer to calculate the optimum service intervals… and we'd recommend ignoring it completely as far as oil changes go. It's not unheard of for an E9X M3's control unit to decide that it will be OK if the engine oil is only changed every 15,000 miles or so, but that's a very bad idea for such a high-performance engine. Rather change the engine oil and filter at the latest every 7,500 miles or once a year, or every 5,000 miles as the vehicle approaches the 60,000-mile mark or if it is subjected to race-track use.
On vehicles equipped with the seven-speed DCT, BMW says that the transmission fluid should be good for life, but experience has shown that changing the gearbox oil every 30,000 miles will result in a longer service life as well as smoother gear changes. A good rule of thumb is to replace the power steering fluid and differential oil at 30,000 miles as well; especially in hard-driven cars, the power steering fluid gets hot and degrades, which will affect the steering feel as well as the system's longevity, and the differential's operation will be smoother if it regularly gets fresh oil.
Spark plugs should be replaced every 36,000 miles, but hard-driven cars will again benefit from a 30,000-mile interval. The spark plugs are particularly important and must be replaced with either OEM or OEM-equivalent units because the S65 engine does its knock sensing via the spark plugs. Other items which need attention every 30,000 miles include the engine air filter, brake fluid, and cabin air filter.