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. If you look you will see that the trigger has three (3)stages:
low, middle, and high. In slow mode you should be pumping on low
speed, 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 other 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 worth for your money.
One of the most important tips is to fill up when your gas tank is HALF
FULL or HALF EMPTY. The reason for this is, the more gas you have in your
tank the less air occupying its 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.
Another reminder, if there is a gasoline truck pumping into the storage tanks
when you stop to buy gas, DO NOT fill up--most likely the gasoline is being
stirred up as the gas is being delivered, and you might pick up some
of the dirt that normally settles on the bottom. Hope this will help you
get the most value for your money.