Refiners Make Switch to Summer Grade Gasoline
According to the U.S. Energy Information Administration (EIA), refiners are switching to make summer-grade gasoline in time for the May 1 compliance date. Summer-grade gasoline lowers the amount of evaporative emissions during warm weather because it is less volatile than winter-grade gasoline.
The volatility of gas is measured by Reid Vapor Pressure (RVP) and determines how quickly the liquid will change into a vapor. The EPA does require lower-volatility gasoline to be used during the summer as a way to reduce some of the emissions created by gasoline use.
In order to make the summer-grade gasoline, refiners spend more per gallon in the production process, which also creates the price of gasoline to rise during warm weather months. As stated by the EIA, the transition typically takes a few months during the spring for refiners to complete the switch from winter- to summer-grade gasoline.