These brake fluids have different colors. Dot 3, dot4, and dot 5 brake fluids have the same color. Pin On Oils Fluids However, it never hurts to check the expansion tank in the engine compartment, as a leak in the line can also cause a gradual loss of fluid. Brake fluid color change . Like most oils, brake fluid changes colour with use. Brake fluid color changes are due to dirt and grime that has collected in the fluid. In principle, they don’t have to, because it is checked and regularly changed as part of the inspection. During a brake fluid exchange, our technicians connect a pressurized machine to the master cylinder. The brake fluid color will change due to regular heating, aging rubber brake lines, moisture, and aging. But a good rule of thumb is to check it during regular oil changes, and expect to change it every four to five years. There are several signs that, without special devices, tell you that the brake fluid is aging and losing its working properti...