ZH 
EN 
Refuelling is second nature to most owners. But is your method right? Here are five common mistakes worth knowing.
1. Running the tank dry before refuelling
Some owners wait until the tank is empty. This is a mistake: with too little fuel the pump is exposed to air and cannot cool properly, and air and contaminants (unfiltered air) can enter the fuel path, upsetting the pump, the engine and the catalytic converter. In bad cases the pump burns out and the catalyst is poisoned.
2. Filling right to the top
Filling to the brim to avoid repeat trips invites overflow, and overflow plus a spark means fire. Overfilling also blocks the vent. With the vent blocked, the tank develops negative pressure as fuel is drawn, causing vapour lock: poor or no fuel delivery. The surging at speed and the failure to start just after refuelling are both caused by overfilling.
3. Leaving the engine running
Refuel with the engine off. A running engine is a heat and spark source next to an open filler.
4. Using the phone at the pump
Put the phone down while refuelling; the risk is small but real.
5. Ignoring the grade the car needs
Use the octane rating the manufacturer specifies. Higher is not automatically better, and the wrong grade costs money without benefit.