If you're the owner of a BMW powered by the popular N63 twin-turbo V8 engine then this is something you should be aware of, but first a little background. The N63 engine has been in production since 2008, powering the previous and current generations of the BMW Series and 7 Series, and the X5, X6, and X7 SUVs. Though it has received numerous updates along the way, its basic bones remain in place. The N63 was also the world's first production vehicle engine to utilize what's called a "hot-vee" layout, meaning its turbochargers are located inside the "V" of the engine.

However, it appears this engine might have a defect. According to Car Complaints, a class action lawsuit was recently filed by two BMW owners, one has a 2011 BMW 550i and the other a 2013 BMW 750li, claiming the engine consumes more oil than it's supposed to.

BMW claims the oil should be changed at "the earlier of 15,000 miles or two years." However, these owners have had to change the oil far more frequently. One owner claims his vehicle used "two quarts of oil every 1,500 to 2,000 miles, while the second says his BMW consumed "one quart of oil every 1,000 miles." Both brought the issue to the attention of BMW dealerships because, at the time, the vehicles were still covered by warranties. The response was less than desirable. One dealer allegedly said the oil "consumption was normal because of the engine." No repairs were made. The other dealer failed to provide any solution and/or explanation.

Meanwhile, both owners had to constantly add engine oil between recommended intervals. The suit also points out BMW was aware of the alleged issue because several technical service bulletins were issued to dealerships about the matter. One 2013 bulletin even issued a new oil consumption standard specifically for this engine because turbocharged engines consume more oil than naturally aspirated engines due to the lubrication requirements.

According to BMW, this is common and not a defect, noting all of its engines can "consume up to 1 quart of engine oil per 750 miles at any time." If so, then the lawsuit mentions this troubling fact: that same 2013 bulletin means a customer needs to add one quart of oil 20 times before reaching the original recommended 15,000-mile interval.

In 2014, BMW started the N63 Customer Loyalty Offer and the N63 Customer Appreciation Program as a result of oil consumption complaints. The loyalty program gave owners the chance to replace their vehicles and authorized dealers to give a $50 credit to owners towards the purchase of BMW merchandise or accessories.

Whether this lawsuit proceeds or not is one thing, but what's clear is that BMW has been fully aware of this problem for some time.