'Big Oil' takes on higher ethanol blends in gasoline A combine unloads corn on farmland near Manteno, Illinois. WASHINGTON, June 5 (UPI) -- The American Petroleum Institute asked the U.S. Supreme Court to strike down a mandate for higher ethanol blends in gasoline "before it's too late." API announced it filed a brief with the Supreme Court over a decision by the Environmental Protection Agency to back so-called E15, gasoline blended with 15 percent ethanol. The trade group, which represents the interests of the U.S. oil industry, said E15 can lead to faulty check-engine signals and cause critical components of certain engines to fail. Bob Greco, director of API's downstream division, said more E15 could lead to problems on the road for consumers. "We are asking the Supreme Court to step in and protect consumers by striking down EPA's dangerous E15 mandate before it's too late," he said in a statement Tuesday. A challenge to E15 was struck down last year in the U.S. Court of Appeals for the District of Columbia. A similar debate erupted when a 10 percent ethanol blend was introduced roughly 30 years ago. The EPA approved E15 for sale last year for cars and light trucks built since 2000. It's not yet widely available at retail gasoline stations. The American Coalition for Ethanol said in April the effort to halt the sale of E15 was "a transparent attempt to protect Big Oil's profitable monopoly."