The Daily O’Collegian

Technically, yes. But the savings are minimal ­— only about $1.50 when buying 10 gallons.

The importance of filling up early in the morning or late at night is overrated, an OSU chemistry professor said.

“That’s a lot of hot air about hot gas, the idea of going at 5 o’clock in the morning,” said Allen Apblett, an associate professor of chemistry.

With gas prices in Stillwater from $2.83 to $3.09 per gallon now, if the gas temperature were to rise to the highest daytime temperature, it would translate into a monetary loss of about 15 cents per gallon.

However, Apblett said that it is highly unlikely that the gas temperature would rise as high as the actual outside temperature because of gas stations’ pump reserves being located underground.

“You’re not going to see a great variation in temperature [of the gas],” he said. “Underground, it’s a whole lot cooler than it is at the surface.”

The U.S. industry standard temperature for which gas pumps are calibrated is 60 degrees Fahrenheit. Most gas pumps dispense the same volume, 231 cubic inches per gallon, at any temperature. Gasoline expands as it gets warmer and, as a result, becomes less dense. This means hot gas has less energy than cold gas, resulting in consumers spending the same amount of money for less power if the temperature of the gas they are pumping into their cars rises.

Apblett measured the actual temperature of the gas at Conoco, 4810 W. Sixth St., at 12:25 p.m. Tuesday. Although the outside temperature was 93 F, the temperature of the gas was only 79 F.

“This would cause about a 1 percent difference in the volume of gasoline from the temperature that they are calibrated for, or an extra 2.8 cents per gallon,” he said.

Apblett took the temperature of the gas at the same location at 7:15 a.m. Wednesday and found that it was 80 F while the outside temperature was only 72 F.

A representative for OnCue was unable to be reached Tuesday. Managers at several service stations declined to comment.

Even with gas prices increasing and the Oklahoma summer temperatures pushing toward the triple digits, the monetary benefits of filling up a tank may be minimal.

However, for students whose wallets are nearly empty, it might be worth it to save 50 cents and fill up in the morning.