BMW used the N54 engine in a wide variety of models from 2006 through 2016. This twin-turbo inline 6-cylinder made appearances in everything from the sedate 740i to the hot M-Coupe. In addition to offering tremendous performance right from the factory, the N54 became well-known as a highly tunable powerplant with significant potential for upgrades.
The N54 was also a fairly reliable engine, so many owners are still happily driving their cars even with the newest models now being 5-10 years old. Unfortunately, oil loss is a common issue on these engines, and it can have various causes. If your N54 seems to be losing oil, follow these simple diagnostic questions to get to the bottom of the problem.
1. Is Your Oil Loss Normal?
Many N54 owners report losing oil, and a certain amount of oil loss can be expected, especially as your engine ages. If you follow BMW's recommended 15k-mile oil change interval, then you will almost certainly replace some amount of oil between changes. In general, you should be concerned if you're consuming more than a quart per 1000 miles or if you notice black exhaust smoke.
2. Is Your Car Leaking Oil?
Some slow oil leaks can masquerade as oil consumption issues. Valve cover gasket leaks are typical on nearly all BMW inline 6-cylinder engines, and these slow leaks can drip directly onto the exhaust, where the oil burns away before ever creating a puddle. The oil filter housing gasket can also leak, sometimes causing oil to drip into hard-to-reach places.
At a minimum, check for these two common leaks before assuming that your car is consuming an excessive amount of oil. An experienced BMW service shop can help find any potential leaks by putting your vehicle on a lift and carefully examining the undercarriage for signs of old oil.
3. Is the Problem Getting Worse?
Steady oil consumption may not be an issue, especially if the problem is relatively small and you can't find any signs of leaks. Worsening consumption may indicate more severe trouble, however. For example, worn piston rings or problems with your turbochargers can create blow-by, a condition that forces tiny amounts of oil into the combustion chamber where it burns away.
Blow-by can severely damage your engine over time and can also impact your car's power and efficiency. Although damage of this type is uncommon on N54s, you shouldn't ignore excessive oil consumption that doesn't have any other apparent cause. A BMW service shop can perform a compression test to ensure that you aren't suffering from internal engine issues.
While oil consumption doesn't always mean that something is severely wrong, it's an issue that you shouldn't ignore. By asking yourself these questions, you can determine whether the problem is significant enough to require a visit to a BMW auto repair shop.