Filler Neck

In order to help prevent refueling with leaded gasoline, the fuel filler neck on vehicles with gasoline engines has a built-in restrictor and deflector. The opening in the restrictor will only admit the smaller unleaded gas nozzle spout, which must be fully inserted to bypass the deflector.

Attempting to refuel with leaded gas, or failure to fully insert the unleaded gas nozzle into the fuel filler neck results in gasoline splashing back out of the filler neck.