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Some Practical Advice

The the current cost of gasoline, there is something you should keep in mind: the temperature when you buy the gas matters.

The meter on the gas pump is keyed to volume and gasoline expands a good deal more than water in response to high temperature. If you mow your lawn with a power mower you have probably seen it happen and missed the significance. You filled the tank on the mower to the top and then started it up. After a couple of minutes you will see the tank overflowing. As the mower heats up, the gas expands and is pushed out of the tank.

The best time to buy gas is in the early morning, the coldest part of the day. Don’t fill the tank all the way to the top, leave room for expansion.

If you make a practice of buying “cold gasoline” you will see an improvement in your mileage.


1 Jack K., the Grumpy Forester { 06.11.08 at 11:10 pm }

…since I have been forced over the last 34 years to become a rump expert in soil properties, just one caveat:

Temperatures in the gas station storage tanks are generally controlled by the surrounding soil within which they are buried. Soils have differing abilities to transmit surface heat energy to lower depths; for example, here in volcano country the silica-rich soils transmit very little heat downward more than a few inches. Depending on the average ambient temperature of the place you live, the daily soil temperature at the depth at which those large gas storage tanks live may not vary all that much from hot days or seasons to cold. On the other hand, filling your ‘cold’ gas tank in the morning and leaving room for expansion is an excellent idea…

2 Bryan { 06.11.08 at 11:28 pm }

Here you get asphalt over the concrete “bunker” for the tanks, and case iron plates over the tank fill valves. The bunkers are supposed to be designed to prevent leaking into the ground water.

To make things even more fun, we have quartz sand instead of silicon, which is why our beaches are “sugar white”.

Our big problem is that the gas comes from above ground storage tanks that are filled from barges, and then distributed in stainless steel tanker trunks, so the tanks are being filled with pre-heated gasoline.