The present invention relates to a method of processing a workpiece comprising contacting a tool and a workpiece to effect a change in the shape of the workpiece, and applying a metalworking fluid to a surface area where the tool and the workpiece are in contact, where the metalworking fluid contains a propoxylate of the formula R—O—(C3H6O)n—H, where R is a branched C6 to C20 alkyl and n is from 3 to 30. The invention further relates to the metalworking fluid, and to a use of the propoxylate as additive in metalworking fluids.