BMW is facing a class action lawsuit for faulty oil filter housings that leak coolant, resulting in owners having to spend thousands of dollars in repairs and replacements. The lawsuit, filed in New Jersey, involves three BMW engines: B46, B48, and B58. The first two are turbocharged four-cylinder engines, while the B58 is BMW’s highly regarded turbo six-cylinder mill. At a time when BMW has improved significantly in reliability ratings, this lawsuit is a reminder that some older models still require careful care and often expensive maintenance.Oil Filter Housing Fails Prematurely According to the plaintiffs, the oil filter housing should last at least 150,000 miles, but the part has needed replacement after 60,000 miles in some cases. Depending on the model, owners have had to pay up to $4,000 for a replacement.“The oil filter housing internal wall structures separating the oil and coolant passages fail and/or warp and/or gaskets sealing the various oil and water passages fail,” said the lawsuit. “This occurrence causes the loss of engine coolant that either leaks into the oil sump or drains externally that can result in engine overheating and/or failure.” The plaintiffs claim BMW changed from cast aluminum engine oil filter housings to cheaper polycarbonate housings in 2011. The automaker is aware of the issue, as communication was sent to dealers late last year informing them of the nature of the issue.Besides select BMW models, some Minis are also named in the lawsuit. Here’s the complete list:2014-2021 BMW 1 Series2014-2021 BMW 2 Series2014-2021 BMW 3 Series2014-2021 BMW 4 Series2014-2021 BMW 5 Series2014-2021 BMW X1, X2, X3, X42014-2021 Mini Cooper2014-2021 Mini Cooper Clubman2014-2021 Mini Cooper CountrymanOne BMW owner not involved in this lawsuit started a petition for BMW to recall vehicles affected by the oil filter housings, which has received almost 600 signatures so far. According to the owner, Eric Coleman, he has spent over $6,000 on the issue for two different BMWs from the 2020 model year. Coleman also pointed out that the problem occurs at around 60,000 miles, not long after BMW’s warranty would have expired.What It Means BMW faced many engine reliability issues in the 2000s when it began switching to turbocharged models. Cooling system failures, VANOS variable valve timing actuator issues, and chronic oil leaks were common. The number of horror stories surrounding engines like the N63 V8 are well documented, too. But over the last few years, the brand has worked through many of these issues and gradually moved up the reliability rankings. The six-cylinder B58 has a particularly strong reputation, which makes the latest lawsuit all the more disappointing. It’s a reminder of the fragility of previous-generation BMWs, where the cars are often only good for 50,000 or so miles before expensive repairs become common. The full extent of the oil filter housing issue isn’t clear yet, but if you’re buying a used BMW with one of these three engines, you should proceed with caution. If the oil filter housing has been done already, you can save yourself thousands.