Abstract: A method of cleaning and replacing fluids of hydraulic brake systems is pided. The method may be implemented to either clean the system and resupply the same type of fluid or replace one type of brake fluid with a new and different type of brake fluid. The method includes the use of an intermediate solvent fluid, generally in combination with air, to dilute the first contaminated brake fluid which, in turn, is displaced by the introduction of the new brake fluid, whether it be of the same or different type. The purpose of the intermediate fluid is to flush the contaminated fluid from the system as well as to alter the properties of the contaminated fluid. The use of the intermediate solvent induces a reversal of the phases of the two respective brake fluids by modifying the density of the fluid with which it is mixed.