TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The zinc anti-wear additive is selected from zinc dialkyl diphosphate (ZDDP), zinc dialkyl dithiophosphate (ZnDTP) or zinc diphosphate (ZDP). The chlorine extreme pressure additive contains chlorine (5-52) wt.%. The sulfonate is sodium, barium or calcium sulfonate. The antioxidant is aminic or zinc phosphate chemical family. The quaternary and twin-chain quaternary compound consists of alkyl dimethyl benzyl ammonium chloride, octyl didecyl dimethyl ammonium chloride, dioctyl dimethyl ammonium chloride, and didecyl dimethyl ammonium chloride.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: In the method, the biocides containing quaternary ammonium compound, twin-chain quaternary ammonium compound, 1,2-benziothiaolin-3 (BIT), 2-methyl 4,5-trimethylene-4-isothiazolin-3-one (MTI), dithio-2,2-bis(benzmethylamide) and phenolic derivative compound (preferably twin-chain quaternary ammonium compound) are added into the formulation. The sulfur or zinc anti-wear agent is blended with biodiesel at 25-85 degrees C to increase the anti-wear properties. In the method, the aminic or zinc phosphate antioxidant (0.1-8 wt.%) is added to the biodiesel metalworking fluids. In step (A), sulfur or zinc additives is added into the biodiesel at 25-30 degrees C to increase its anti-wear properties. In step (B), chlorine or phosphorus additives is added into the biodesel at 25-30 degrees C to increase the load bearing carrying capabilities. In step (B), aminic antioxidant is added to the biodiesel at 25-30 degrees C. Preferred Composition: The biodiesel metalworking fluid composition comprises (wt.%): biodiesel (65-90, preferably 76), sulfur or zinc phosphate anti-wear additives (0.1-4, preferably 1), chlorine or phosphorus or boron extreme pressure additives (0.1-9, preferably 3), emulsifiers (3-12) (preferably nonyl phenol 6 moles (5)), antioxidant (0.1-3) (preferably aminic antioxidant or zinc dithiophosphate antioxidant (2)), corrosion inhibitors (0.5-12) (preferably sodium sulfonate (3) and dicyclohexylamine (4), and triethanolamine (2)), and quaternary and twin-chain quaternary ammonium compound (0.5-4) (preferably 1). Preferred Components: The biodiesel metalworking fluids are emulsifiable and dilutable with water. The biodiesel is derived from methyl or ethyl ester, where the carbon chain of the biodiesel is 14-18C and the Cetane Index of the biodiesel is 50-90. The sulfur anti-wear additives contain a sulfur (0.5-38)%. The nonylphenol ethoxylate is 4-6 moles of ethylene oxide and the non-ionic alcohol ethoxylate is 4-5 moles of ethylene oxide. The amine based corrosion inhibitors are dicyclohexylamine and triethanolamine. EXAMPLE - No suitable example given.