Received this email this morning. Not sure if it's true, but at today's fuel prices, everything's worth a try.
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ONLY BUY OR FILL UP YOUR VEHICLES 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 denser the
fuel, when it gets warmer petrol expands, so buying in the afternoon or
in the evening.... Your litre is not exactly a litre.

In the petroleum business, the specific gravity and the temperature of
the petrol, diesel and jet fuel, ethanol and other petroleum products
play an important role. A 1degree 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 vapours that are created, while you are pumping.
All hoses at the pump have a vapour return. If you are pumping on the
fast rate, some of the liquid that goes to your tank becomes vapour.
Those vapours 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 TANK IS HALF
FULL.

The reason for this is, the more fuel you have in your tank, the less
air occupying its empty space. Petrol evaporates faster than you can
Imagine. Petroleum storage tanks have an internal floating roof. This
roof serves as zero clearance between the petrol and the atmosphere, so
it minimizes the evaporation.

Unlike service stations, here where I work, every truck that we load is
temperature compensated, so that every litre is actually the exact
amount.

ANOTHER REMINDER, IF THERE IS A FUEL TRUCK PUMPING INTO THE STORAGE
TANKS, WHEN YOU STOP TO BUY, DO NOT FILL UP - most likely the
petrol/diesel is being stirred up as the fuel 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 maximum value for your money.

 

WOW!!!!!!!!!!! is this true?????

 

There's been another thread about this and same tips were listed.

 

http://www.snopes.com/inboxer/household/gastips.asp

 

Sorry. Lots of myths that aren't true. Here goes.

At the depth that the tank is buried underground, the temperature is pretty constant. Ground temperature after 5 ft is around 65F degrees no matter what the above temperature is. So no matter what time of day you pump the gas, it's pretty much going to be around ground temperature. Think of a heat pump for a home. It's just a big ol radiator that's buried under ground and its functionality depends on the FACT that the ground temperature is pretty constant and mild.

Gasoline does vaporize, but only to a certain point. If gasoline is in a close container, it will vaporize until the air in the tank is saturated. After that, no more can vaporize. (think of 100% humidity. You can't have more than 100% humidity. If you did, then you get precipitation.) So in actuality, when you pump gas into a tank, you're already pushing out the air that's 100% saturated with gasoline vapors. Therefore, the new gas being pumped in can't evaporate because its in a saturated environment.

The last one is partially true. There is sediment in the holding tank and when fresh fuel is delivered, it can potentially stir up the sediment, but all pumps must have filters installed to prevent the dirt and sediment from clogging or damaging the pumps, seals, valves, etc used to deliver the fuel to the vehicle, so its not a serious as you think. The gas station may not necessarily do things to protect the customers' vehicle, but they'll do what ever it takes to protect the expensive equipment that they purchased with their own money.

 

how much would you save from doing these methods? like a dollar per fill up? lol