The LL avgas situation is odd because while we have quite a number of additives to reduce knocking (ugh MTBE) valve erosion has been one of the listed reasons f

The LL avgas situation is odd because while we have quite a number of additives to reduce knocking (ugh MTBE) valve erosion has been one of the listed reasons for not using it. Yet, most aircraft engines have strict servicing guidelines and mandating replacement valves/seats with a more resistant design could have been done 40 years ago as part of engine overhaul/rebuild guidelines. Then the usage would have slowly declined. Yes its expensive, but so is GA aircraft maintenance. *MTBE was another of those chemicals where the replacement was quite likely just as bad if not worse than the original. Similar to the refrigerant bans where we went from a chemical that broke down in the atmosphere fairly quickly (and caused ozone holes doing it) to one that lingers basically for eternity and causes global warming.