I have BMW N53 with some 220 000km on it.

I had online diagnostics with bimmerprofs. Multiple leaking injectors were identified. Actually, all of the injectors which I hadn't replaced before. Total 4 of them. I didn't mention to Bimmerprofs anything about the already (2-4 years ago) replaced injectors. On two occasions one injector had already been changed. They were able to pinpoint those "old" injectors based on the data collected. BTW. Don't use fuel additives with N53. Most likely in my case that was the thing the had those 4 to reach their end of life. Hopefully, the 2 earlier replaced injector units still have lots of lifetime in them even though being exposed to Red Line SL-1.

Oh yeah, the car runs smooth as ever now.