SAN FRANCISCO – ExxonMobil Corp. placed stickers on dispensers in California and Arizona to alert drivers that the amount of energy received from each gallon of gasoline changes depending on the outside temperature, the San Francisco Chronicle reports. Tesoro is the only other oil company that has put such messages on its pumps.

Despite the stickers, both Exxon and Tesoro say that their position hasn’t changed in regard to their opposition to installing temperature-adjusting pumps, as proposed by federal legislation introduced last week.

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

The oil industry's opposition to temperature-adjusting pumps centers around the fact that higher summer temperatures and colder winter temperatures cancel each other out, with the cost of gasoline costing consumers approximately the same as with the temperature-adjusting pumps. Therefore, the cost of new pump installation isn’t justified.