Leading petroleum producers, including Saudi Arabia and Exxon Mobil Corp., are aggressively arguing that plenty of crude oil remains for world consumption, a move to counter critics who contend crude output is about to plateau, according to the Wall Street Journal on Thursday. The argument, known as the "peak-oil" theory, has provided intellectual backing for the boom in crude prices and sowed doubts among some policy makers about crude's long-term reliability as an energy source. Such doubts, coupled with concern over sky-high prices, have added impetus to the search for oil substitutes -- including in Washington, where President Bush declared...