The federal government is allowing dirty diesel fuel at the pump longer than it had originally required. The extension applies to highway-grade diesel and expires on Oct. 15, 2006.

Prior to Oct. 15, retail fuel may contain a "slightly higher" sulfur content than previously mandated, according to a recent announcement from the Environmental Protection Agency. The earlier retail deadline was Sept. 1.

Hurricane hits along the refinery-rich Gulf Coast apparently did not contribute to the government's relaxation of the rule. The delay, claims EPA, is a response to oil-industry requests for more time to flush sulfur contaminants out of distribution channels.

After the deadline, ultra-low-sulfur diesel, rated at 15 ppm, becomes the standard for all highway-bound diesel cars and trucks. The summer "transition" period allows 22 ppm diesel to be marked and sold as 15-ppm diesel.

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Early sulfur cuts prepare fleet owners for clean-burning engines that arrive by January 2007. At that time, diesel cars and trucks will feature tailpipe emission controls, such as particulate filters. The 15-ppm fuel is a "critical" component for the filters to work effectively, EPA says. Extending the deadline may prolong manufacturers from launching 2007-compliant engines next year, the agency adds.

Fuel terminals have until Sept. 1 to comply with the rule. Oil refineries still must produce ultra-low-sulfur diesel by June 1, 2006. Highway diesel fuel currently has a sulfur rating of 500 ppm.

Off-road diesel is not yet regulated, with average sulfur content well over 3,000 ppm. But it eventually will match up with highway-grade diesel, changing to 500 ppm by 2007 and 15 ppm by 2010.

Link: EPA final rule