By Sudeep Reddy, The Dallas Morning News Knight Ridder/Tribune Business News
May 12--Crude oil broke through a key barrier Tuesday, closing above $40 a barrel as doubts grew over whether the world's major oil suppliers can meet surging demand.
Low inventories and unrest in the Middle East have buffeted prices for months as growing demand in Asia and the United States absorb available supplies.
Saudi Arabia has called on the Organization of Petroleum Exporting Countries to increase supplies.
But analysts remain skeptical, and the A