Oil prices turned lower Monday, failing to hold on to earlier gains as the stubborn glut of oil in storage continued to weigh on the market. U.S. crude futures settled down 54 cents, or 1.21%, at $44.20 a barrel on the New York Mercantile Exchange. Brent, the global benchmark, fell 46 cents, or 0.97%, to $46.91 a barrel on ICE Futures Europe. Oil prices were pulled down by falling prices for gasoline and diesel, as well as…