I have a Golf R with a Bilstein coil-over set up. 35,000 street miles so far and 10+ track days. My last 3 Porsches..all coil over (Ohlins), over 20k road miles and 30+ track days each. Never a drop of oil. The last issue that I can recall is when my Audi blew a strut after I hit a pothole about 20 years ago….I just had it rebuilt. I have no idea on Koni….I never had them. No BS…a shock is the last thing that i would expect to leak.