Thread: Gas Buying Tips
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Old 09-27-2007, 12:28 PM   #11
JackG
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Join Date: Mar 2005
Location: South Carolina
Posts: 530
Quote:
Originally Posted by cfos
So... if the temp thing is true...

Suppose you gas up in the afternoon and go straight home and park it in the garage. Ambient temperature, in most parts of the country drop overnight, thus, you would argue that you would have more gas in your car in the morning, right? If so, would that cancel out the afternoon shortage?
Actually, the opposite. If you filled up with warm gas, then parked it full and it cooled off, the tank would not be full in the morning. Gas expands when hot, and contracts when cool.

I agree with the others that say the temp thing actually doesn't make any appreciable difference. The temperature of the underground storage tanks stays pretty consistent from day to night, the air entering the tank as the gas is pumped out is small compared to the existing gas and air in the tank, so it heats/cools to the tank's temp quickly. It also takes a fairly large swing in temps to make any real difference in the relatively small amounts that we put in our cars.

In the end we're talking about a couple of pennies worth... I've got better things to worry about.
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