This is another issue I'm fixing. This little valve stops all the oil from draining to the sump when the engine is turned off. What happens eventually is that the engine is a little noisy and has the oil pressure light on for a few seconds after turning it on. Basically it takes a few seconds to build the pressure when all the oil has drained. This valve is a non serviceable part and is attached to the oil filter housing, BMW suggests to replace the entire housing if this valve fails.
As it turns out this valve can be removed and that means you can get an aftermarket replacement, which I did.
The failure, for me at least is that the valve doesn't seat properly after a while, which I've demonstrated. The new one is a ball end and always seats properly.