Biodiesel is becoming increasingly available at retail fuel stations and from bulk delivery dealers. Farmers are large users of diesel fuel because most tractors and other equipment are powered by diesel engines.

What effect using biodiesel will have on engine warranties is a question producers will need to answer.

""Most agricultural equipment manufacturers do not warranty their engines if they are operated on B100, which is 100 percent biodiesel,"" says John Nowatzki, North Dakota State University Extension Service agricultural machine systems specialist. ""However, all do allow blends of up to 5 percent with petroleum diesel. All engine warranties from the major tractor manufacturers also require both the petroleum diesel and the blended biodiesel to meet the American Society of Tests and Measurements (ASTM) specifications for diesel and biodiesel fuels. Some manufacturers' warranties of farm tractors and equipment do allow higher blends, some even up to B100, so it is important to check with the equipment dealer or manufacturer for each specific engine."

People who make their own biodiesel particularly need to be concerned about the possibility of voiding engine warranties because of the difficulties of consistently producing high quality biodiesel. Small-scale producers need to have their fuels regularly analyzed to make sure their product meets ASTM D6751 standards.

""Farmers unknowingly may be using biodiesel blends because biodiesel commonly is added to the petroleum diesel marketed today to increase lubricity,"" Nowatzki says. ""Since Oct. 15, 2006, most diesel fuel sold at retail locations in the U.S. is ultralow sulfur diesel fuel (ULSD) that has different lubricating qualities than diesel previously available. ULSD diesel fuel has substantially reduced levels of sulfur.""

The purpose of lowering the sulfur content is to allow the application of newer emission control technologies on engines, which is intended to substantially lower the emissions of nitrous oxide and particulate matter into the atmosphere. However, the process used to reduce the sulfur content in diesel also reduces the fuel's lubricating properties, resulting in increased wear on the various parts of the engine's fuel injection system. Some suppliers are blending biodiesel, which has excellent lubricating characteristics, with petroleum diesel.

To get the latest information on where biodiesel is available, check the National Biodiesel Board Web site at http://www.biodiesel.org/ and then click on ""buying biodiesel.”

""Make sure that you are buying biodiesel, not just crude, unprocessed vegetable oil,"" Nowatzki says. ""Ask the distributor to provide certification that the biodiesel meets ASTM D6751 standards."

NDSU Agriculture Communication