The 40-year old ban on most U.S. crude exports is set to be loosened after Mexico’s state-owned oil company asked for an exception. Petroleos Mexicanos is in talks with the U.S. Commerce Department to import 100,000 barrels a day of light crude to increase Mexico’s gasoline production and improve refining. Pemex, as the world’s ninth-largest oil producer is known, would send its heavy oil to U.S. Gulf Coast refineries in exchange. Oil producers including Exxon Mobil Corp. (XOM) and Continental Resources Inc. (CLR) have called for the U.S. to end the restrictions, saying booming domestic output reduces the need to keep supplies at home. U.S. oil supply has increased by 66 percent in the past five years, and a majority of that growth is in light oil from shale rock. It would be another incremental allowed export “that will help relieve the pressure on pricing of domestic light oil, […]