A synthetic metalworking fluid (MWF) was formulated with the specific purpose of achieving both necessary functional properties such as lubricity and corrosion inhibition as well as compatibility with microfiltration. The synthetic formulation was assessed to have comparable lubricity and corrosion inhibition relative to a commercial formulation. The microfiltration performance with the newly formulated synthetic was superior to a previously reported study utilizing a commercial formulation. This suggests that successful formulation is possible that preserves both functionality and ease of recycling. However, microfiltration performance was found to be extremely sensitive to trace contaminants in the phosphate ester used in the formulation. Therefore, care needs to be taken to develop appropriate specifications for chemicals used for formulating membrane compatible metalworking fluids. (c) 2005 Elsevier B.V. All rights reserved.