1. Fill up your car or truck in the morning when the temperature is stillcool Remember that all service stations have their storage tanks buriedbelow ground; and the colder the ground, the denser the gasoline. When itgets warmer gasoline expands, so if you're filling up in the afternoon orin the evening, what should be a gallon is not exactly a gallon. In thepetroleum business, the specific gravity and temperature of the fuel(gasoline, diesel, jet fuel, ethanol and other petroleum products) aresignificant. Every truckload that we load is temperature-compensated sothat the indicated gallon age is actually the amount pumped. A one-degreerise in temperature is a big deal for businesses, but service stationsdon't have temperature compensation at their pumps.
2. If a tanker truck is filling the station's tank at the time you want tobuy gas, do not fill up; most likely dirt and sludge in the tank is beingstirred up when gas is being delivered, and you might be transferring thatdirt from the bottom of their tank into your car's tank.
3. Fill up when your gas tank is half-full (or half-empty), because themore gas you have in your tank the less air there is and gasolineevaporates rapidly, especially when it's warm. (Gasoline storage tankshave an internal floating 'roof' membrane to act as a barrier between thegas and the atmosphere, thereby minimizing evaporation.)
4. If you look at the trigger you'll see that it has three deliverysettings: slow, medium and high. When you're filling up do not squeezethe trigger of the nozzle to the high setting. You should be pumping atthe slow setting, thereby minimizing vapors created while you are pumping.Hoses at the pump are corrugated; the corrugations act as a return pathfor vapor recovery from gas that already has been metered. If you arepumping at the high setting, the agitated gasoline contains more vapors,which is being sucked back into the underground tank so you're gettingless gas for your money. Hope this will help ease your 'pain at the pump'.
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