Get more gas when filling up...

[Flycaster]

From a guy in the oil industry

"

I've been in petroleum pipeline business for about 31 years, currently
working for the Kinder-Morgan Pipeline here in San Jose, CA. We deliver
about 4 million gallons in a 24-hour period from the pipe line; one day
it's diesel, the next day it's jet fuel and gasoline.

We have 34 storage tanks here with a total capacity of 16,800,000 gallons.
Here are some tricks to help you get your money's worth:

1. Fill up your car or truck in the morning when the
temperature is still cool. Remember that all
service stations have their storage tanks buried below
ground; and the colder the ground, the denser the gasoline. When it gets
warmer gasoline expands, so if you're filling up in the afternoon or in the
evening, what should be a gallon is not exactly a gallon. In the petroleum
business, the specific gravity and temperature of the fuel (gasoline,
diesel, jet fuel, ethanol and other petroleum products) are significant.
Every truckload that we load is temperature-compensated so that the
indicated gallonage is actually the amount pumped. A one-degree rise in
temperature is a big deal for businesses, but service stations don't
have temperature compensation at their pumps.

2. If a tanker truck is filling the station's tank at the time you want
to buy gas, do not fill up; most likely dirt and sludge in the tank is
being stirred up when gas is being delivered, and you might be
transferring that dirt 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 the more

gas you have in your tank the less air there is and gasoline evaporates rapidly,
especially when it's warm. (Gasoline storage tanks have an internal floating

'roof' membrane to act as a barrier between the gas and the atmosphere, thereby
minimizing evaporation.)

4. If you look at the trigger you'll see that it has three delivery settings: slow,

medium and high. When you're filling up do not squeeze the trigger of
the nozzle to the highsetting. You should be pumping at the slow setting,

thereby minimizing vapors created while you are pumping. Hoses at the pump are
corrugated; the corrugations act as a return path for vapor recovery from gas that

already has been metered. If you are pumping at the high setting, the agitated

gasoline contains more vapor, which is being sucked back into the underground

tank, so you're getting less gas for your money. Hope this will help ease your 'pain

at the pump'."

[Hawkeye]

I got this in the email a couple months ago too

What I don't understand is:
1. If you are filling on slow, doesn't that give the gas more time to evaporate out?
2. With the sludge and stuff from the tankers, the pumps already pull from the bottom of the tank (otherwise they would run out before the gas was gone) so wouldn't it be better to only get a little sludge?
3. If you are making the extra effort and stopping to fill up when half empty / full, you would probably be wasting more gas pulling into the station, restarting your car after pumping and then exiting the station than you would by losing vapors filling up when you are actually empty.