Only buy or fill up your car or truck in the early morning when the ground temperature is still cold.
Remember that all service stations have their storage tanks buried below ground. The colder the ground the more dense the gasoline, when it gets warmer, gasoline expands, so buying in the afternoon or in the evening….your gallon is not exactly a gallon. In the petroleum business, the specific gravity and the temperature of the gasoline, diesel and jet fuel, ethanol and other petroleum products plays an important role. A 1-degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.
When you’re filling up, do not squeeze the trigger of the nozzle to a fast mode.
You will see that the trigger has three (3) stages: low, middle, and high. You should be pumping on the slow or medium modes, thereby minimizing the vapors that are created while you are pumping. All hoses at the pump have a vapor return. If you are pumping on the fast rate, some of the liquid that goes to your tank becomes vapor. Those vapors are being sucked up and back into the underground storage tank so you’re getting less fuel for your money.
One of the most important tips is to fill up when your gas tank is HALF FULL.
The more gas you have in your tank, the less air you have occupying the empty space. Gasoline evaporates faster than you can imagine. Gasoline storage tanks have an internal floating roof. This roof serves as zero clearance between the gas and the atmosphere, so it minimizes the evaporation. Unlike service stations every truck that we load is temperature compensated so that every gallon is the exact amount.
If there is a gasoline truck pumping into the storage tanks when you stop to buy gas, DO NOT fill up.
Gasoline is being stirred up significantly as the gas is being delivered, and you might pick up some of the dirt that normally settles on the bottom.