LeSabre V8-307 50L VIN Y 4-bbl (1984) Exhaust System Technical Service Bulletins
A small diameter fuel tank filler tube is used on catalytic converter equipped vehicles to prevent the larger service station pump nozzle, used for
leaded fuels, being inserted into the filler tube. Since the use of leaded fuels contaminates the catalysts, rendering them ineffective, the use of
unleaded fuels is mandatory in catalytic converter equipped vehicles.