U.S. oil refiners are planning a heavy slate of plant overhauls in the second quarter, with total production this month off 8.5 percent compared with the start of the year, according to data from the U.S. Energy Information Administration. Early spring and winter traditionally are heavy periods for U.S. refinery maintenance. But refiners are planning more upgrades than usual in the first half of 2019 to avoid fall and winter shutdowns as they prepare to meet coming low-sulfur standards. This year’s maintenance schedule and higher crude prices helped push U.S. gasoline prices to a national average of $2.83 a gallon last week, up 26 percent since the start of the year, according to data from the American Automobile Association. U.S. crude futures rose 32 percent in the first quarter. […]