leaky or missing gas cap can save as much as a gallon of gas every 15 days 。 Refer to the Manual Below for Vehicle's Compatible Details. 。 locking gas caps are OEM quality both in construction and materials as well as deterrent to fuel theft and vandalism. A gas/fuel cap performs three very important functions; safety of the vehicle's occupants. Stant 10413 Truck Locking Fuel Cap: Automotive. Buy Stant 10413 Truck Locking Fuel Cap: Fuel System - ✓ FREE DELIVERY possible on eligible purchases. A quality locking mechanism deters fuel theft and vandalism 。 Original equipment performance and safety standards 。 OEM quality construction and materials 。 Replacing an old. a vehicle with a missing or inoperative fuel cap will allow 17 pounds (22 gallons) of gasoline to evaporate over the period of one year. Emissions: Gasoline vapors emit hydrocarbons which dissolve the earth's ozone layer and cause smog. 。 。 。. gasoline vapors will be present around your car at all times. Those vapors can be ignited by a random spark or flame and are very dangerous if you are involved in an accident or rollover. Fuel Economy: According to Sun Oil Company research. fuel economy and reduce emissions. Safety: Without a fuel cap.