Several types of Biodiesel were tested, including Biodiesel derived from another oil crop, winter rapeseed. Rapeseed is grown extensively in Idaho, Canada and Europe to produce Canola. Biodiesel made from Canola has very similar properties to the Biodiesel made from soybean and other plant oils. In the Idaho study, the Biodiesel test fuels were (100%) rapeseed ethyl esters (REE), rapeseed methyl esters (RME), 50% blends of REE or RME, and 20% blends of REE or RME with petrodiesel. The reference fuel was conventional (Texas) No. 2 petrodiesel ("2D"), a low-sulfur diesel formulation mandated nationally by the EPA since 1993 .