Gasoline has a much higher coefficient of thermal expansion than water, which means that a gallon of gas at 0°C weighs more than a gallon at 20°C, since it has expanded with heat and gotten less dense. Underground storage tanks are fairly thermally insulated, so you really get more of an effect seasonally rather than across the day, but it's there. The gas currently sitting in the hose is fully susceptible to this effect, so ironically if you only fill up a little (to avoid vapors), you get a bigger effect from temperature in the afternoon to offset the savings. OTOH, it also means that pumping just a little at a time and only in the morning probably helps more.
Interesting? :jointsmile:
L Rag Reviewed by L Rag on . Pump Gas in the Morning Interesting? :jointsmile: Rating: 5