in our other cars the butterfly thingy or whatever its called was always
covered with crap, preventing it from working properly. the gum gutter cleaned it up great. the sl is totally different in design, we haven't really
figured out how it works- refering to the round plunger thing.
according to the manufacturers website its safe:
Specialties, Cleaners, Lubricants and Tire Repair
Concentrated cleaner cleans carburetor and metal parts
Safe for use with catalytic converters & sensors
---- not that i believe everything i read