| Reuters | Oil turns negative on strong dollar after hitting 18-month highs ... Reuters Oil prices turned negative after earlier hitting 18-month highs on Tuesday, the first trading day of 2017, as the U.S. dollar rallied to its highest since 2002. Oil Prices Boosted by Optimism Over Production-Cut Promises Oil Climbs to 18-Month High as Kuwait and Oman Fulfill OPEC Cuts Oil pivots sharply lower on anxiety over adherence to 2017 output curbs |