What are the precautions when using brake fluid?
3 Answers
When using brake fluid, the following precautions should be taken: 1. Regularly replace the brake fluid. Over time, the performance of brake fluid may degrade due to moisture absorption and chemical changes, affecting driving safety. Therefore, the brake fluid in use should be replaced periodically. There is no specific time frame for replacement, but it is generally recommended to replace the brake fluid when inspecting the master cylinder and wheel cylinder piston cups during vehicle maintenance. 2. Store brake fluid properly. Most automotive brake fluids are made from organic solvents, which are volatile and flammable. Keep them away from fire sources, and take precautions against fire and moisture. Avoid exposure to rain, sunlight, and moisture absorption to prevent deterioration. 3. Do not mix different types of brake fluid. Different products use different raw materials, additives, and manufacturing processes, and mixing them may cause turbidity or sedimentation, which is hard to detect without careful observation. This not only significantly reduces the performance of the original brake fluid but also may lead to clogged pipelines and brake failure due to sediment particles. When changing brands, always flush the system with the new product before adding it. 4. Choose the correct brake fluid product code. Generally, selecting brake fluid according to the vehicle's user manual is the most reasonable and reliable approach. Automobile manufacturers conduct thorough research and extensive vehicle tests before recommending brake fluids. In addition to specifying the standard product code and brand, the manual usually provides alternative options. Users should prioritize the standard product code and brand and only consider alternatives when the standard product is unavailable.
I've been driving for over a decade and have accumulated considerable experience with brake fluid usage. First, it's crucial to understand that brake fluid is hygroscopic—over time, it absorbs moisture, which lowers its boiling point and can lead to vapor lock under high temperatures, compromising braking performance. Therefore, it's generally recommended to replace it every two years or 40,000 kilometers. Always tighten the cap securely during refills to prevent moisture ingress, which can damage the brake system. Never mix different types of brake fluid, such as DOT3 and DOT4, as this can cause sedimentation and clog the lines. During each maintenance check, I insist on having the mechanic use professional equipment to measure moisture content—replacement is immediate if it exceeds 3%. Store the bottle in a cool, dry place, as direct sunlight can degrade the fluid's effectiveness. After changing the fluid, ensure all air is bled from the system; otherwise, the brake pedal will feel spongy.
Having worked in a repair shop for eight years, I've encountered numerous cases of brake failure caused by brake fluid issues. When replacing it, you must strictly follow the specification required by the vehicle manual. German cars mostly use DOT4, while Japanese cars prefer DOT3. Using the wrong grade can cause rubber seals to swell. Always wear corrosion-resistant gloves during operation, as this stuff can burn your skin upon contact. Keep the filling port absolutely clean – even a speck of dust can clog the ABS pump. New brake fluid must be used up immediately after opening; exposure to air for over an hour causes moisture absorption and renders it useless. A crucial reminder: never try to save money by adding unknown liquids as substitutes. Last year, a car owner mixed in engine oil and had to replace the entire brake assembly.
