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New mixes of gas confront drivers

Vernon Gerlach, of Mitchell, puts away the gas nozzle after filling up his lawnmower gas can Thursday afternoon in Mitchell. (Sean Ryan/The Daily Republic)

A blend of gasoline South Dakotans put in their vehicles is changing.

Stern Oil Company President Gillas Stern — whose company’s corporate headquarters is in Freeman — said gas stations are now selling two forms of 87 octane gas, neither of which is traditional regular with 87 octane. Instead, it will now be blended.

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One blend will have 83 octane mixed with 91 premium, and another is an 83 octane gas mixed with 10 percent ethanol. Both blends produce an 87 octane mix. On Oct. 1, the regular, non-blended 87 octane gas was no longer available.

“Previously, before October 1, typical gas stations had 87, 89 and 91,” Stern said, referring to octane ratings. “Now the typical product slate will be 87, 87 and 91.”

Octane is the measure of the ignition quality of gasoline. The higher octane fuel has a higher stability under compression and a more complete burn, and is generally associated with better engine performance.

The switch from regular 87 to blended versions is because of the Renewable Fuel Standard, passed by the federal government in 2005. The law requires fuel refiners to reach a certain threshold of renewable fuels, which is why there’s a push to use lower octane gasoline blended with more ethanol.

United States refiners must sell an overall volume of 16.55 billion gallons of renewable fuels per year. Each individual refiner must sell a specific amount of ethanol in its gas, depending on individual sales, or face federal fines.

“Oil companies have to meet a certain renewable fuel standard,” Stern said. “They have to market and sell so many gallons per year.”

Dawna Leitzke, the executive director of the South Dakota Petroleum and Propane Marketers Association, said refiners are making the new mix of 83-91 to replace the 87 regular and give their consumers a similar product. A version of 89 with 10 percent ethanol, labeled 89 E-10 at the pump, has already been available but could become more scarce, according to Stern. Many stations will replace it with the 87 E-10.

“That will be up to each station if their consumers want that product,” he said.

Leitzke expects to see the evenly mixed 83-91 blend eventually be eliminated because of price vs. performance. Stern estimated the 83-91 blend of 87 octane to be about 22 to 30 cents more expensive than the 87 E-10.

“We’re all creatures of habit, and you’re going to pick up the cheaper product, whether a gallon of milk or gallon of gasoline,” Leitzke said.