This specification covers biodiesel fuel blend stock, B100, in Grades S15 and S500 for use as a blend component with middle distillate fuels. This specification prescribes the required properties of diesel fuels at the time and place of delivery. The requirements stated here may be applied at other points in the production and distribution system when provided by agreement between the purchaser and the supplier. The biodiesel specified shall be mono-alkyl esters of long chain fatty acids derived from vegetable oils and animal fats. The product shall undergo chemical analysis for flash point, methanol, water and sediment, kinematic viscosity, sulfated ash, oxidation stability, sulfur, copper strip corrosion, cetane number, cloud point, acid number, carbon residue, total and free glycerin, phosphorus, reduce pressure distillation temperature, atmospheric equivalent temperature, combined calcium and magnesium, and combined sodium and magnesium.