Old school, yes. These days, vehicles have knock sensors that can detect detonation before you can hear it, and adjust for it. So, what's good for California should be good enough for the rest of us? As far as I know, the fuel does still change between seasons. Ironically, season changes are when those of us on the auto repair industry see more failed fuel pumps. Interesting. Asks the driver of the big silver bomb? (Aka... Professional fuel delivery driver.)