Does gasoline expand and contract significantly with temperature changes?
2 Answers
Gasoline does not expand and contract significantly with temperature changes. Here are the relevant details: 1. Basic knowledge: Gasoline has a much lower density than water, so one liter of gasoline weighs less than one kilogram. At room temperature (25°C), taking 93-octane gasoline as an example, its density is approximately 0.725 kg/L, meaning one liter of gasoline weighs around 0.7 kg—still far from one kilogram. When the temperature rises, its volume increases, and consequently, its density decreases slightly. From this perspective, the thermal expansion and contraction of gasoline do affect its density to some extent, though the change is minimal. 2. Thermal expansion of gasoline: Gasoline does expand and contract with temperature changes. For every 1°C increase in temperature, the volume of gasoline expands by approximately 0.12%.
Last time I refueled, the experienced mechanic shared a little trick with me: gasoline expands and contracts significantly with temperature changes. For example, between 20°C in the morning and 30°C at noon, a 60-liter fuel tank can vary by the volume of half a bottle of mineral water. So the most cost-effective time to refuel is early morning or late at night when the ground temperature is lower, as the gasoline in the station's storage tanks has a higher density. I've tried it myself—filling up the same amount of money in the morning or evening can give you an extra ten kilometers or so. In summer, don't fill the tank too full, as the expanding gasoline might overflow through the vent, not only wasting money but also posing a safety hazard. Gas stations charging by volume does put car owners at a slight disadvantage, since colder gasoline is more economical.