Tips for replacing your gas cap include choosing the correct model for your vehicle, cleaning the fuel tank opening before installing the new cap and determining if you need a locking gas cap. Prevent loss of your new gas cap by installing a retaining ring that attaches it to the vehicle so it is not accidentally left behind when fueling the vehicle.
Manufacturers use different styles of gas caps for their vehicles. Supply the auto parts store with the make and model of your vehicle to ensure you get the right one. If the new gas cap does not fit the opening, it cannot seal the tank, which is necessary to reduce evaporation and keep the fuel free of debris.
If the gas cap has been missing for a few weeks, the opening likely has attracted some dust and dirt due to the accumulation of oily materials in the fuel. Use a clean rag to remove this dirt so it does not fall into the tank and foul the fuel filter.
While many manufacturers include fuel access doors that operators release from inside the vehicles as of 2015, older cars may not have this feature. Selecting a locking gas cap provides an additional layer of protection so thieves do not siphon gas from the tank.