[CassiesMan]

It could be a lifter. Basically, a hydraulic lifter could be bleeding down oil in the lifter body. Fixing it, dunno. I would say either take it to a BMW dealership and see what they say (could be pricy, might just wanna go to a mechanic you trust). Might be able to fix it by using some commercial engine flush product in the oil and drive the car for a while then replace oil and filter. If that doesnt work, then you would need to replace the lifter, and that is gonna be pretty expensive.