Summer-grade gasoline typically contains 2% butane, a colorless, odorless gas that is used in lighter fluid, for example, according to AAA. In the winter, gasoline contains more butane, to help vehicles start up in colder weather.
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The summer blend burns cleaner and contributes less to air pollution, which is more of a threat in hot weather.
“Summer formula gasoline increases fuel efficiency and helps prevent smog-causing compounds from being released into the atmosphere,” said Craig VanBuren, director for the Laboratory and Consumer Protection Bureau for the Michigan Department of Agriculture and Rural Development. “MDARD inspectors will conduct on-site testing during the summer gas season, which runs from June 1 to September 15.”
Fuel terminals were required to make the switch by May 1, according to the Energy Information Administration but gas stations have until Saturday to make the switch to summer-grade gasoline.
Gas stations in several counties in southeast Michigan will be monitored by MDARD beginning Saturday when gas stations are required to only sell the summer grade-fuel, to ensure that the smog levels remain low.
“Gov. Whitmer has taken bold actions to protect Michigan’s environment, which we echo at MDARD,” said director Tim Boring in a statement. “Our department is committed to protecting Michigan’s environment as our industry continues to implement climate-smart practices focused on combating climate change in Michigan.”
The EPA regulates the “Reid Vapor Pressure,” or RVP, of gasoline sold at retail stations during the summer. RVP measures the volatility of gasoline. The higher the RVP, the faster it will evaporate and contribute to ground-level ozone. Enforcement of a low-RVP requirement means that the state will continue receiving federal highway funding.
To ensure low smog levels, MDARD will monitor the ozone levels in Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne counties.
Gas retailers in these counties must only sell or dispense gas that does not exceed 7.0 pounds per square inch vapor pressure, according to the department.
Summer-grade fuel is more expensive to produce and people tend to drive more as the weather warms, increasing demand — yet another factor in higher summer prices.
