Fluids & Lubricants
Brake Fluid
Keep every stop firm -- fluids and greases built for brakes.
Brake fluid is the hydraulic muscle behind every stop -- it turns pedal pressure into clamping force at the wheels. It also absorbs moisture over time, which lowers its boiling point, so fresh fluid isn't optional; it's what keeps the pedal firm when the brakes get hot.
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Which brake fluid do I need?
Use the DOT rating your vehicle calls for -- usually DOT 3, DOT 4, or DOT 5.1, which are glycol-based and can be topped off with each other in a pinch. Never mix in DOT 5 (silicone); it's a different chemistry and isn't compatible with ABS systems. Because fluid pulls in moisture, most makers recommend a full flush every two to three years.
Related: Brake Lubricant, Cleaners, Bleeder Screws, All Fluids & Lubricants.