ExxonMobil, the largest oil and gasoline producer in the nation, is now alerting consumers in two states to the fact that the energy content of a gallon of fuel varies as it expands due to temperature increases. This results in motorists paying a higher price for a given amount of energy as the temperature rises.

The oil and gas conglomerate began placing the disclaimer stickers — a “Motor Fuel Measurement Notice” — on its gas pumps in Arizona and California last month.

“We spotted them for the first time this month,” said Judy Dugan of the stickers. She is research director of the Santa Monica-based Foundation for Taxpayer and Consumer Rights, which has been active in monitoring summertime gas temperatures in the state.

“It is simply a reminder (to customers) that the dispenser sells motor fuel by volume,” said Exxon spokeswoman Prem Nadir in a statement. “This is how fuel has traditionally been sold at retail in the continental United States.”

By agreeing to place the seals on their retail gas pumps, the oil companies are acknowledging that the concept of hot fuel is legitimate, says Dugan.

ExxonMobil joins Tesoro, which began putting the disclaimers on its pumps in July.

Due in part to the local climate, California motorists purchase gasoline that is at least 15 degrees warmer than the government standard of 60 degrees, according to the Santa Monica advocacy group. The fact that gasoline expands when it heats up and is sold by volume results in a hidden increased cost to motorists, which can be as much as an extra three cents per gallon more, they say.

Oil company representatives say that higher temperatures during the summer months and lower readings during winter should effectively cancel each other, and there is no need for fuel adjustments on the nozzles, which they allege, would be prohibitively expensive.

Dugan’s organization has been lobbying for petroleum companies to compensate for lost energy due to hot fuel by installing a device with a temperature gauge within the gasoline pumps, which would then adjust the pump meter for the current temperature. The instrument would function as a computer inside the fuel pump, measuring how hot or cold the gas is and adjust the flow accordingly.

Most oil companies have refused to adopt such measures.

The Santa Monica nonprofit and other consumer organizations support a proposal that was put forth in July at the National Conference on Weights and Measures that would develop guidelines for gasoline operators to choose to install temperature compensation devices. The proposal was not considered because it failed to garner the votes necessary for consideration, but advocates of the device are hopeful that the measure will be approved next year.

“When an item neither passes nor fails, it goes back to the Laws and Regulations Committee,” explained Michael Cleary, who was chairman of this year’s conference.

Cleary, who is the executive legal counsel for the California Department of Food and Agriculture, thinks that there is a good possibility the idea could resurface at next year’s meeting.

“I believe that a debate will come up,” he said. “This is a good proposal.”

The Owner-Operator Independent Truckers Association, an independent trade association representing private drivers and independent operators, has conducted scientific research on hot fuel, says Norita Taylor, the organization’s spokeswoman, after many of the organization’s members began complaining of lower gas mileage in certain parts of the country.

“We took 100 samples of gasoline at different temperatures from around the United States,” Taylor told The Argonaut. “At first we suspected that there could have been tampering with the gasoline.”

Their findings showed that truckers were losing gas mileage when the fuel was hotter because the liquid expands as temperatures rise, causing the fuel to lose energy.

“The real issue has always been temperature, not tampering,” Taylor pointed out.

The Los Angeles County Bureau of Weights and Measures has been tracking hot fuel for quite some time.

“I haven’t seen gasoline temperatures in Los Angeles County below 60 degrees this year,” said Jeffery Humphreys, deputy director of the bureau.

Senator Claire McCaskill of Mississippi has introduced legislation, called the F.A.I.R. (Future Accountability In Retail) Fuel Act that would require the installation of technology that would regulate gasoline temperatures at all retail gasoline distributors within six years.

“Some say you get what you pay for,” the senator said. “That’s just not the case at the gas pump in the summertime. We have the technology to change that, and there’s no good reason not to utilize it.

“The big oil companies are the most profitable corporations in the universe, and yet they continue to fight against consumer protections while we pay the price. The least we can do in Congress is ensure consumers are getting what they pay for.”

In addition to requiring all retail gas stations to install the new temperature compensating technology within six years, the F.A.I.R. Fuel Act would offer assistance for retailers to comply, and impose penalties for those who fail to ensure that consumers are receiving the gas that they pay for.

Oil companies in recent years have posted record profits.

The Foundation for Taxpayer and Consumer Rights supports McCaskill’s proposed legislation.

“This bill would rectify the problem,” Dugan asserted.

“(McCaskill’s bill) is a good start,” Taylor added.

Over 95 percent of gas stations in Canada employ this technology, says Taylor. In addition, Hawaii also uses gas temperature control devices.

“If it’s good enough for Canada and Hawaii, why isn’t it good enough for the lower 48 states?” Taylor asked.

If California were ever to adopt this technology, the accuracy of the devices would need to be examined.

“Our responsibility would be to test the accuracy of the pumps and to make sure that the pumps are displaying accurate information about the gasoline’s temperature,” said Humphreys.

Although Los Angeles Assemblyman Mike Davis has introduced legislation on hot fuel in the State Legislature, Dugan does not believe that it will provide sufficient protection for motorists.

“What we are hoping for is real consumer protection,” Dugan said. “[ExxonMobil] has funds that it uses to help dealers with infrastructure, and which could be used to buy nozzles that adjust fuel volume for higher temperatures.

“ExxonMobil, America’s most profitable corporation, owes drivers more than just a sticker in tiny print.”