With increased emissions came catalytic converters, with the catalytic converter came the use of unleaded gasoline. Catalytic converters, which were mandated in the United States from 1975 forward, are emission control devices. The platinum matrices within the converters can become fouled by lead additives present in leaded fuels. GM started using these Unleaded Gasoline Only decals on their gas cap filler doors to alert new owners that unleaded gasoline was required for their engine, because of the new emission standards, requiring the implementation of catalytic converters.
The Vehicle Fitment Guide is to be used as a general reference. The data has been provided by our suppliers and manufacturers and may contain errors or incorrect data. Always refer to a professional to verify correct fitment for your vehicle.