Pumping Gas: Your Chain E-Mail Is Wrong

By Marty Padgett June 9th, 2008

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You already know that gas prices hurt, and maybe you also know a way to find the best price in your area. When it comes to getting the most out of the pump, though, some drivers are pumping me for information on driving half-full, half-empty, or close to "E."

The reason: a series of chain mails that have been zipping through The Great Cloud of Internetdom for months. The version I got a few weeks attempted to argue that gas vapor, cold gas, warm gas, and dirty gas could all be avoided--and could save you money and time. It sounds logical, doesn't it?

Not according to the AAA's Geoff Sundstrom. Most of us are better off paying attention to the running condition of our cars, Sundstrom says: "Consumers would be better served to concentrate on keeping their vehicles maintained, consolidating trips and errands, and adjusting their driving to avoid prolonged idling, hard braking, and sudden acceleration."

So what's true and what's false when it comes to pumping gas? Here's Sundstrom's take on the tips floating around the Web:

1) Only buy or fill up your car or truck in the early morning when the ground temperature is still cold.

It doesn't matter, Sundstrom says. "The idea that gasoline expands when warm and contracts when cold is true," he says, "but the amount of fuel that can be saved by filling up when the temperature is cooler would be so minuscule as to be hardly worth the effort. There is some research taking place in California on the cost to consumers of 'hot fuel,' but conclusive results have not been reported to our knowledge."

2) When you're filling up, do not squeeze the trigger of the nozzle to a fast mode.

Gas can vaporize as it pumps, "but only in extremely small quantities," Sundstrom adds. "The reason the vapor is recovered at the pump is to help limit air pollution from evaporating gasoline. Pumping more slowly may be of some assistance in getting more gasoline for the dollar, but it is not going to alter your fuel bill in any meaningful way."

3) If there is a gasoline truck pumping into the storage tanks when you stop to buy gas, DO NOT fill up.

The warning that there is enough sediment in underground storage tanks that can harm your vehicle is "mostly an outdated idea," Sundstrom says. "Anything that does make its way into the underground tank will be strained out by an internal filter. Your vehicle's engine is further protected by the gas filter in the fuel line."

Posted in : Driving, Shoppers |

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2 Responses to “Pumping Gas: Your Chain E-Mail Is Wrong”

Just saw this article in the paper. It confirms what a friend of mine told me. He’s a geologist and also a high school science/geology teacher, and said that the temp of the tanks underground are at a steady 50 degrees year round (approx.), 24/7. Note the line in the following story, that I changed to all caps. (It’s a newspaper article where people talked about installing a geothermal heating/cooling system in their house.)

“It costs $15,000 to $25,000 to install a ground source heating system. Nelson estimates it will take about five years for the savings to pay for the system.

”A lot of people don’t realize the amount of heat stored below ground right below their feet,” J. David Reynolds, president and founder of Atlantic Groundsource LLC, the firm that designed and is installing the system. ”They think it’s just stones and dirt.”

“IN THE NEW ENGLAND AREA, ONCE YOU DIG ABOUT SEVEN FEET BELOW THE FROST, THE GROUND IS ABOUT 50 DEGREES YEAR-ROUND, HE SAID.”

Hence…it doesn’t matter what time of day you pump the gas…or even time of year. It’s all pretty much the same 50 degrees. Think about it. If you have a pool behind your house, it takes weeks for it to warm up in the spring. One hot day barely makes a dent. A big tank of liquid (or a lake) takes a LONG time to heat or cool…weeks. So the gas which rushes from the underground tank to your car barely gets above ground before it is measured and enters your tank, and it really can’t warm up in that time. Touch the metal nozzle when you’re pumping gas, and prove it to yourself…it is COLD!

The in-ground temperature of the gas doesn’t really vary that much, although it certainly can once it is in the pump & hose above ground, in the heat.
However, running several gas stations taught me one thing that will virtually always be true… DO NOT buy your gas when a tank is being, or was very recently, filled.
Sediments (in terms of solids) aren’t the problem, at all - moisture is.
The previously mentioned underground coolness, combined with the warm air allowed in whilst filling (and, the warmth of the gas itself, if it’s hot going in) and from vents, WILL cause condensation in the underground tank, and water is in virtually every gas station’s tanks across the land. This water WILL mix around when the tank is filled, and water in your car’s gas tank, is generally the result.
Gas station owners do use “drying” chemical agents (such as dry gas) to keep the problems minimized, as best they can, but the problem is virtually never eliminated.
A small amount of water in your car’s gas tank, may not be much problem, but, a larger amount will be. This can occur at any time of year. During the winter, fill your car from a tank that’s just had a delivery, drive home & park it, and you may not start your car in the morning - due to a frozen gas line.