Gas Tips

The following snip has been posted a dozen times around the internet.  I received it in an e-mail from my favorite propagator of urban myths so I have to be a little careful simply posting without some caveats.  It’s interesting but the source is as yet undetermined.  The jury is out regarding the accuracy of the gas tips.  The earliest reference I can find on the web is from September 23 but the Snopes reference is from February of 2007.

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 pipeline; one day it is diesel, the next day it’s jet fuel and gasoline. We have 34 storage tanks here with a capacity of 16,800,000 gallons. Here are some tricks to help you get your money’s worth:

  1. Fill up your car/truck in the morning when the temperature is still cool. Remember that all service stations have their storage tanks buried below ground. The colder the ground the denser the gasoline. When it gets warmer gasoline expands, so if you’re filling upin the afternoon or evening, what should be a gallon is not exactly a gallon. In the petroleum business, the specific gravity and temperature of the fuel (gasoline, jet fuel, diesel, 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. ( Which means “too bad for us”……..)
  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 are 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 because the more gas you have in you 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. (ed.: Another reason not to wait until you are empty is that you are gradually burning out the fuel sender unit in your gas tank. The fuel pump/sender unit is all one part on most cars now……….replacement is roughly $600)
  4. If you look at the gas trigger (at the pump) 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 high setting. 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.

Originally posted on

%d bloggers like this: