Humm... interesting post. I've never heard of this product. I'm gonna have to ask my German parts store about it!
Maybe it goes in the gas tank? Liqui Moly makes other intake valve and fuel injector cleaners that you just pour into the fuel tank. Like these...
But I have not
used these above injector cleaners in my 135i.
I also have used a product from Motul that is designed to be used on D.I. engines, a fuel injector cleaner. With that product you just add a can to the fuel tank. Then drive the car. It does say to change the oil afterwards. I think with any of these products and oil change afterwards is advised.
I used this Motul injector cleaner in my 135i, but did not notice any difference in performance before/afterwards.
Motul direct injection fuel cleaner?
Btw... The Liqiu Moly Drosselklappenreiniger (Throttle Valve Cleaner) when I used that on my e39 v8, 535i, its produces a white smoke. Not black. Also lots of back fires and popping noises when you inject that stuff into the intake manifold. It did seem to make my old e39 run smoother afterwards. AND I changed teh oil afterwards too, just for my peace of mind.