What is Automotive Brake Fluid?
3 Answers
Automotive brake fluid is the liquid used in hydraulic braking systems. More information about automotive brake fluid is as follows: 1. After prolonged use, the brake pump will exhibit varying degrees of wear. 2. Automotive brake fluid does not undergo chemical reactions, is unaffected by high temperatures, and will not corrode, soften, or cause expansion to metals and rubber. 3. When replacing brake fluid, it is important to note the replacement cycle, which varies depending on different climatic conditions. 4. During replacement, it is essential to use brake fluid of the same grade as originally specified for the vehicle, and brake fluids from different brands should not be mixed.
When I take my own car for maintenance, I find that brake fluid is a particularly important hydraulic oil in the braking system—it's that transparent or light-colored liquid that transmits pressure to the brake pads on each wheel when the pedal is pressed, helping the car stop. Its main components are glycol-based substances with a high boiling point, preventing overheating and boiling during high-speed driving, which could lead to brake failure. But here's the problem: over time, it absorbs moisture from the air, lowering its boiling point and potentially causing vapor lock, making the brakes feel spongy or even fail. I recommend changing it every two years. I use a test pen to check if the moisture content exceeds the limit, and I make it a habit to inspect the dashboard lights or changes in braking distance before daily driving—these small habits greatly enhance safety. Different car models use DOT specifications, such as DOT 4, which has a higher boiling point and is suitable for long-distance driving. Don’t skimp and buy counterfeit fluid, as it may corrode system components.
Last week, I was chatting with a friend about car maintenance when she asked what brake fluid is. I explained it's like the blood in your body that flows through the brake lines—when you press the pedal, the pressure transfers to the brake pads to slow down the car. There are mainly DOT 3 and DOT 4 types, which are water-based and prone to absorbing moisture. This lowers their boiling point and can cause bubbles, leading to brake failure. I recommended changing it roughly every 20,000 kilometers to prevent accidents. Doing it yourself isn’t hard—just siphon out the old fluid and refill with the new, matching the specifications to ensure cleanliness. As a beginner, learning this stuff has made me more confident driving at night. Normally, if you notice the brake pedal feeling softer or the warning light comes on, check immediately for low fluid levels or excessive moisture affecting overall performance—don’t delay.
