Abstract: A conditioning additive for an oil-in-water emulsion metal working bath includes a copper-amine complex and may further include a molybdenum-amine complex. The complexes may comprise the reaction product of alkanolamines and salts of the metals. The additive may further include pH stabilizing agents, wetting agents, corrosion inhibitors, emulsifiers and surfactants. The additive inhibits microbial growth, stabilizes the emulsion, improves lubricity, prevents corrosion and improves the finish of parts produced therewith.