Oil futures closed at a four-month high Tuesday as global economic reports point to improving conditions. Benchmark light sweet crude rose 68 cents to $96.24 a barrel on the New York Mercantile Exchange. Oil has risen almost $3 a barrel over the last four trading sessions. Brent crude, used to price international varieties of oil, was up 71 cents to $112.42 a barrel on the ICE Futures exchange in London. U.S. retail gasoline prices rose slightly overnight to a national average of $3.31 a gallon (3.8 liters), which is about 7 cents below the price a year ago, according to three price-tracking organizations