UNIVERSITY PARK, Pa. -- The sulfur content in on-road transportation diesel fuel was greatly reduced in recent months, and it is critical that operators of off-road diesel equipment know the sulfur content of the fuel they use in diesel engines in their operations, says an expert in Penn State's College of Agricultural Sciences.

Sulfur content in diesel fuel is regulated by the federal government, according to Dennis Buffington, professor of agricultural engineering. "Before 1993, the allowable sulfur level in diesel fuel was 5,000 parts per million," he says. "From 1993 until earlier this year, allowable sulfur was 500 ppm. However, starting in June 2006, the ultra-low sulfur requirement was implemented, which means that the sulfur content must be no higher than 15 ppm for 'on-road' transportation fuel."

The government is requiring the use of the ultra-low sulfur fuels to reduce the concentrations of sulfur compounds in the environment, Buffington explains. When sulfur content is reduced in diesel fuel, one consequence is that lubricity of the fuel is greatly reduced. "Lubricity is the ability of the fuel to provide lubrication to reduce wear between moving parts of the diesel injector pump and the fuel injectors," he says.

Fuel used for off-road functions -- such as farm, construction and forestry operations -- is exempted from the ultra-low sulfur requirements, at least for the present time. "You can still legally use the low sulfur fuel with 500 ppm sulfur," Buffington says. "But the problem is that not all fuel suppliers are carrying both the 'on-road' (15 ppm) and the 'off-road' (500 ppm) diesel fuel."

How does a farmer or forester know the sulfur content of the fuel being delivered to them? The only way is to ask the fuel supplier for the sulfur content, Buffington says. "If the supplier doesn't know, insist that he or she find out and inform you," he advises.

Buffington says if your current fuel supplier can only deliver 'on-road' diesel fuel to your farm tank, then you have three alternatives:

--Ask your supplier to verify that a lubricity agent has been added to your fuel.

--Add a lubricity agent yourself to the ultra-low sulfur fuel to provide the protection needed in your diesel engines or

--Find a supplier who will deliver 'off-road' diesel fuel.

Many lubricity agents are available at the big-box stores as well as at auto supply shops, but Buffington notes these can be quite expensive. "A more cost-effective approach is to use biodiesel," he says. "Biodiesel has virtually no sulfur content but has excellent lubricity properties. Using just a B1 blend (1 percent biodiesel with 99 percent regular diesel fuel) improves lubricity of ultra-low-sulfur diesel fuel by as much as 65 percent."

To get up-to-date information on where biodiesel is available in Pennsylvania, check the Web site for the National Biodiesel Board at http://www.biodiesel.org/. Click on "Guide to Buying Biodiesel." Under the heading of DISTRIBUTORS, click on "Click here for a national map of biodiesel distributors." Then click on "Pennsylvania" on the map. "Make sure that you are buying biodiesel and not just crude, unprocessed vegetable oil," Buffington cautions. "Ask the distributor to provide certification that the biodiesel meets ASTM D6751 standards."

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(EDITORS: Contact Dennis Buffington at 814-865-2971 or by e-mail at deb2@psu.edu.

Writer/Editor Jeff Mulollem Phone: 814-863-271p E-mail: jjm29@psu.edu