In another post of the forum I stumbled over Keropur. So far I did not know such additives at all. The manufacturer applied the stuff with pictures of cleaner valves. Sounds quite good for a layman like me for the time being. But are there also serious tests, in which the testers looked at the engine before and after the use of the miracle remedy, for example with an endoscope? Has it been proven that these additives really benefit the engine because they remove residues or is the only money tailoring? The videos at YT don’t leave a good feeling with me, because there is more guessed and appreciated, instead of really well-founded checks. I have a G7 with 122 hp and usually fill E10 at Hem, and I drive rather little (75,000 km in ten years).