Another possible cause is a cracked oil filter housing. The oil filter housing is located on the side of the engine block. If it cracks, it can allow oil to leak into the coolant system.
Finally, a faulty head gasket can also cause oil to get into the coolant system. The head gasket is located between the engine block and the cylinder head. If it fails, it can allow oil to leak into the coolant system.
If you suspect that oil is getting into your BMW's coolant system, it's important to take it to a mechanic as soon as possible. Driving with a contaminated coolant system can damage the engine.
Here are some signs that oil may be getting into your BMW's coolant system:
1. The coolant level is low, even after you have added coolant
2. The coolant is discolored or milky
3. There is oil on the dipstick or in the coolant reservoir
4. Your BMW's engine is overheating
5. Your BMW is experiencing decreased performance
