When refilling a brake master cylinder, what type of fluid should always be used?

Using OEM-specific brake fluid is crucial because the manufacturer designs brake systems with specific fluid characteristics in mind. These fluids are formulated to meet the requirements of the vehicle's braking system, such as viscosity, boiling point, and compatibility with system materials. Utilizing the recommended fluid ensures optimal performance, reliability, and safety of the braking system.

Different types of brake fluids, such as DOT 3, DOT 5, and synthetic fluids, are created to meet particular specifications. For instance, DOT 5 fluid is silicone-based and not compatible with systems that use glycol-based fluids (like DOT 3 or DOT 4). Each vehicle manufacturer may specify a distinct formula to deliver the best braking performance. By adhering to the OEM specification, you can prevent issues like brake failure, increased wear on components, or degradation of seals, which can lead to leaks or other serious malfunctions.