Background
Most manufacturers, in the continued search to lower costs and instill planned obsolescence in their products, are replacing parts that were traditionally made of metal or alloys with plastic. This is a particularly dangerous practice when it comes to parts subject to drastic temperature changes, like the cooling system.
The Issue
As of 2025, the most recent generation of engines found in mainstream BMWs is the modular B series engine. This is a very well designed engine, with modern features like variable timing, turbocharging, electronic heat management, and more.
One of the most concerning weak point is the decision to go to a plastic oil filter housing. The part s subject to constant extremes of heat and cold, and as you can imagine, plastic over time does not hold up well to those conditions.
Once the plastic becomes brittle, it deforms and cracks, causing a major coolant leak. A coolant leak can very quickly cause engine overheating, leading to catastrophic engine failure.
Popular BMW Models With a Plastic Oil Filter Housing
Most 3, 4, 6, and 8-cylinder BMW engines of the B family have a plastic Oil Filter Housing, including:
- 2015+ BMW 3-Series, 4-Series, X1 SAV, X2 SAV, X3 SAV
- 2016+ BMW 5-Series G30, all variants
- 2018+ BMW X5, X6
Symptoms of a Failing Oil Filter Housing
- Dreaded 'Top Off Engine Coolant' message on the iDrive screen
- Low coolant in either coolant expansion tank
