Trans-esterification of four vegetable oils; canola oil, greenseed canola oil from heat-damaged seeds, processed waste fryer grease and unprocessed waste fryer grease, was carried out using methanol, and KOH as catalyst. The methyl esters of the corresponding oils were separated from the crude glycerol, purified, and characterized by various methods to evaluate their densities, viscosities, iodine values, acid numbers, cloud points, pour points and gross heat of combustion, fatty acid and lipid compositions, lubricity properties. and thermal properties. The fatty acid composition suggests that 80-85% of the ester was from unsaturated acids. Substantial decrease in density and viscosity of the methyl esters compared to their corresponding oils suggested that the oils were in their mono or diglyceride form. The lubricity of the methyl esters, when blended at I vol%, treat rate with ISOPAR(R) M reference fuel. showed that the canola methyl ester enhanced the fuel's lubricity number. From the analyses performed, it was determined that the ester with the most potential for being an additive or a substitute for diesel fuel is the canola methyl ester, whose physical and chemical characteristics are similar to diesel fuel. (C) 2003 Elsevier Ltd. All rights reserved.