Gasoline expands as temp increases, but how much? Is there a simple formula relating temperature to volume?

Question

I live in Arizona and want to know how much money I save if I fill my tank at 7 a.m. instead of 5 p.m. on a typical day where temperature may vary 25 degrees or more.

Answer 1

GAS DOES NOT GET ANY HOTTER IN THOSE UNDERGROUND TANKS. SO IT DONT REALLY MATTER WHAT TIME YA BUY GAS, TRUST ME.

Answer 2

The reason you should fill up in the morning is because your gas tank will be cooler and therefore when you put the gas in your tank, the air that comes out will not be as toxic.

The gas temperature doesn't change much underground like it is.

Answer 3

Here's the formula.  You'll have to convert F to C.

The change in volume = 0.00108 x original volume x temp change

So for example, if you put in 10 gal of gasoline into your car when the temperature was 20C.  Then later in the day the temperature rose to 22C (temperature change of 2C).  The calculation would look like this

The change in volume = 0.00108 x 10 gal x 2C

The change in volume = 0.0216 gal

In other words, the increase in volume would be 0.0216 gal more (total volume would be 10.0216 gal).

I've crunched the numbers for your situation.  There is an insignificant change in volume.  Plus, the gas tanks are stored underground.  Underground, the temperature remains nearly constant...this is the same reason so many wine cellars are underground, because temperatures barely fluctuate.

Answer 4

Gasoline expands when temperatures rise and contracts when temperatures fall. The energy content is directly related to its weight, not its volume. Therefore, the energy content of gasoline does not correspondingly increase when gasoline volume expands. The standard coefficient of gasoline’s expansion/contraction equals 0.069 % per degree Fahrenheit

• 513.8 million gallons of gasoline sold in the summer 2007 will be attributable to the thermal expansion of gasoline.

• Consumers will pay a hot fuel premium of about $1.5 billion in the summer 2007

Domestic Policy Subcommittee Majority staff

Oversight and Government Reform Committee

House of Representatives

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