My personal research is this is false. I have changed plenty of flats using CO2 and not had another flat on the tire for months. I do air the tire with a floor pump before the next ride so maybe that is why but I haven't had recurring flats on the tire that had CO2 on the road. My husband and the LBS pounded into my head on a skinny road tire air it up before each ride unless you are a fan of leaving the bike open for a pinch flat. I have never had a CO2 filled tire be low in enough to call it flat 18 hours though, 10-20lbs pressure yes but I have seen this on regular old air too.