What about the 15,000 mile oil change?
BMWs have nearly always had extended oil life recommendations. New BMWs with “full maintenance warranty” [Ultimate Service Maintenance Program] limit free oil services to 1 per year or when the service indicator tells you; depending upon driving conditions and habits, this averages around 12-16K miles, which is in line with their 15K mile recommendation.
The oil service on the M52 engine should be performed every 4500 miles, or half the recommended interval of 9000 miles. By that time, even if the oil isn’t completely broken down- chemically speaking- it’s usually pitch black and should be changed simply to prevent sludge deposits from forming. The newer M54 engine burns cleaner than the M52, and can indeed go 7500 miles between changes- again, half the recommended interval of 15000 miles.
Oil analysis has proven that modern oils like BMW 5W30 High Performance Synthetic will last approximately 12K miles before breakdown, so it’s certainly possible to wait until that point, but there are two reasons why we recommend replacement earlier than that.
First, though oil technology has improved, the filter has not changed. There is risk that the paper oil filter insert will fail before then…
Second, all oil eventually reaches the point where it can take no more particulate matter in suspension, reaching a point of saturation. It’s not hard to speculate where all the gunk will go from that point on:
Particularly troubling was this ‘plug’ of sludge that prevented the oil from draining from the vehicle until it was removed manually:
In any case, BMW’s recommended 15K or higher oil service interval on modern vehicles (E36 or later) is as ludicrous as is the notion of a low-maintenance high-performance automobile, and they are gambling the health of your engine with your money. Do yourself a favor and do regular oil services at half the recommended interval. It’s cheap insurance and will add to the resale value should you choose to do so at a later date.
In summary, we believe the engine will not fail prematurely due to the extended miles on the oil; however, the long-term life of the engine might be extended if more frequent servicing is done. It’s very important to frequently inspect all fluids, belts, tires and hoses.
A visit to Munich Motorsport every 6 months or 5000-7500 miles to change the oil and filter, adjust tire pressures and perform a comprehensive inspection can not only save you money over the life of your BMW, it could also save you the inconvenience of a breakdown.