Membrane microfiltration is a promising technology that has been shown to extend metalworking fluid (MWF) life by eliminating contaminants while allowing the fluid to stay in use. However, the efficacy of this technology is compromised by the clogging of the filter pores in a process known as membrane fouling. In this paper the fouling issue is addressed by the development of a semi-synthetic MWF specifically designed to reduce fouling of microfiltration membranes. The composition of the designed MWF is discussed and compared with a commercial MWF. Cross-flow microfiltration fouling tests were carried out in low pressure, high velocity conditions on ceramic α-alumina membranes. Several common MWF components are shown not to be factors of membrane fouling on these membranes. The flux of the designed fluid was found to reach an immediate steady-state at about twice the value of the steady-state flux of the tested commercial fluid. SEM imaging was used to further evaluate membrane fouling by each fluid. The machining capabilities of the designed fluid were examined in terms of cutting forces and machining temperature.