[T.Smith]

Gasoline is sold by volume, not by energy level (I don't know the term. Therm?), right? So, why should the oil companies have to increase the volume because of ambient temperature? Am I not understanding the physics/economics involved?

[Eric in the Ozarks]

When I worked for a major oil company we figured there was just under a penny extra profit in the "shrink" of gasoline. We never counted this penny as income because it was never collected by the company at wholesale; it was simply a "pennysworth" that disappeared between the refinery loading rack and the retail gas station as the gasoline cooled down.
Heavy oils, including N6 fuel, is sold as "net gallons corrected to 60 degrees" no matter what the temperature is at loading. The API pulishes a conversion scale for these heavy oils based on API gravity and temperature. If Ralph Nader & Company want to increase the cost of gasoline by removing and replacing every gas pump in the US, they might borrow a few of Ralph's millions to help do it.

[Ouderkirk]

The bureau of weights and measures certifies the pumping equipment to be sure that the volume paid for is the volume delivered. Since the measure of a fluid ounce is based on weight the volume of a gallon a gasoline is different than a gallon of water since the Specific Gravity of water = 1 and the SG of gasoline would depend on the formulation. Assume an SG of 0.82.