This SAE Recommended Practice was prepared to provide engineers, designers, and manufacturers of motor vehicles with a set of minimum performance requirements in order to assess the suitability of silicone and other low water tolerant type brake fluids (LWTFs) for use in motor vehicle brake systems. These fluids are designed for use in braking systems fitted with rubber cups and seals made from styrene-butadiene rubber (SBR), or a terpolymer of ethylene, propylene, and a diene (EPDM).
In the development of the recommended requirements and test procedures contained herein, it is concluded that the LWTFs must be functionally compatible with braking systems designed for SAE J1703 and SAE J1704 fluids. To utilize LWTFs to the fullest advantage, they should not be mixed with other brake fluids. Inadvertent mixtures of LWTFs with fluids meeting SAE J1703 are not known to have any adverse effects on performance, but not all combinations have been tested. Vehicle manufacturer’s recommendations should be followed where indicated. These fluids are not necessarily suitable for use in central hydraulic or pumped systems and are not intended for use below temperatures of -50 °C (-58 °F). Brake fluids covered under this document are not required to tolerate water and extreme caution should be exercised to prevent accidental entry of water which might lead to brake failure. Other performance characteristics of these LWTFs not covered in this document are discussed in Appendix A.