cleaner ! the dealer does not recommended it because of the design of the injector ... So people with pre 94 has been using all kind of injectors cleaners on their cars .. and causing the high injectors failure rate .. maybe we need to have a survey and ask people with failed injectors if they have used fuel injectors cleaners or not. I have never used fuel injectors cleaner on my car ever, a month ago I get a bottle of redline fuel injectors cleaner and put it in my tank .. bang .. a month later I have injectors problems ..coincidence or the cleaner solvent have corroded and killed the injector pintle !?