If you are serving SRAM hydraulic disc brakes, there is only one fluid you can use, DOT 5.1 brake fluid. DOT 5.1 is the only recommended fluid for SRAM hydraulic disc brakes. DOT fluid is much better at managing water, which, over time, always finds its way into any brake system. DOT fluid makes any water in the system part of the fluid. DOT fluid is less compressible than mineral oil- DOT was specifically invented to be incompressible—a key attribute of any high-performance hydraulic fluid.