Brake system has been considered as the most important safety system for a vehicle. Performance of the Brake system depends upon various factors like purity of brake fluid, material and construction of rubber hose, rubber seal performance etc. The purity of the brake fluid is one of the most vital factor and incompatibility of the rubber hose with brake fluid causes contamination of the brake fluid. This intern can cause shrinkage / swelling of master, slave cylinder rubber seals. The change in the dimensional of the rubber seals directly affects the performance of the brake system.In order to evaluate the performance of the brake system, Styrene Butadiene Rubber (SBR) and EPDM elastomers with different % of ethylene and varying ENB content were considered for brake fluid compatibility test. These rubber materials were tested in the different brands of DOT 3 brake fluid. Design of experiments has been carried out on EPDM material with different % of ethylene and varying ENB content to find out suitable and optimized combination of the rubber and brake fluid brands. The selected combination from the experiments has been taken further for component level tests.Traditionally, methods of test for the compatibility of brake fluid with rubber hose may not address the actual vehicle service conditions. To addresses the actual conditions; a new methodology has been developed. Hoses were successfully tested and their performance was compared in terms of volumetric expansion of rubber seal, brake fluid contamination, brake pedal sinking, and pedal efforts. This methodology can also be extended to detect contaminations in other types of fluids used in the automobile.