Seasonal Fuel Blends Explained: Summer and Winter
August 8, 2019
If you’re filling up your vehicle with gasoline throughout the summer and winter months, you have most likely never noticed a difference in how your car runs year-round. You have your local gas station operators to thank for that. In fact, there are different blends of fuels based on the season – mainly summer and winter. Why is this? Continue reading for an explanation of seasonal fuel blends.
Reid Vapor Pressure (RVP)
Volatility is a property of the gas that defines its evaporation characteristics. RVP is an abbreviation for "Reid Vapor Pressure," a common measure of and generic term for gasoline volatility.
During both the summer and winter months, gasoline evaporates at different rates depending on the temperature outside. Fuel with a lower RVP evaporates slower while higher RVP fuel evaporates faster. Winter blends need to have a higher RVP (up to 15.0 psi) for engines to start and operate properly during cold weather. As summer approaches, lower RVP fuels (down to 7.0 psi) are used to prevent unnecessary evaporation due to rising temperatures.
Fuels with a higher RVP cost less to the consumer because additives are what lower the fuels RVP. Therefore, gas stations can often sell their gas at a lower price in the winter vs. summer. In “Why Gas Prices Fluctuate,” we mentioned how one of the most influential factors of fluctuating gas prices is the time of year.
Federal Gasoline Standards
Gas stations must switch fuels based on the season in order to comply with regulations directed by the Environmental Protection Agency (EPA). According to the EPA, they regulate the vapor pressure of gasoline sold at retail stations during the summer ozone season (June 1 to September 15) to reduce evaporative emissions from gasoline that contribute to ground-level ozone and diminish the effects of ozone-related health problems.
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