The Financial Post reports in its Tuesday edition that Chevron, Canadian Natural Resources and Suncor Energy are pressing the operators of the expanded Trans Mountain pipeline to change certain key specifications to improve the value of the crude the conduit is carrying. A Bloomberg dispatch to the Post reports that the drillers are asking Trans Mountain to lower the vapour pressure and acid levels of the crude it will allow to pass through the line, saying that the current limits are reducing the value of the oil that is shipped and restricting where it can be refined. Trans Mountain is owned by the Canadian government. The complaints are marring the start of the pipeline's long-delayed expansion, which almost triples the volume of crude that can be shipped from Alberta to the Pacific Coast. Oil producers already had been upset by the high tolls they are being charged to use the line -- partly a result of construction setbacks that caused the project's price tag to balloon sixfold to $34-billion -- and are arguing the shortcomings should allow them to pay less. Chevron says TMX's vapour pressure limit exceeds U.S. Environmental Protection Agency caps on storage tanks at California refineries.