How many liters of brake fluid is needed for a complete replacement?
2 Answers
A complete brake fluid replacement requires 1 liter. Methods to determine if brake fluid needs replacement are: 1. Open the brake fluid reservoir cap; if the fluid appears turbid or black, it needs replacement; 2. Drive at a normal speed above 40km/h and perform a hard brake; if the braking distance significantly increases, replacement is needed; 3. If the brakes feel soft or unstable during normal driving, replacement is required. Reasons for replacing brake fluid include: 1. Moisture or impurities from the air can enter through the reservoir vent, lowering the boiling point of the brake fluid; 2. During prolonged braking, the brake lines can develop vapor lock, leading to reduced braking force or brake failure.
I usually drive a family sedan for daily commuting. When replacing all the brake fluid, it generally requires about 1 liter, and in most cases, 0.8 to 1 liter is sufficient. This depends on the size of the car—for example, a compact car might only need 0.5 liters, while a midsize SUV could require over 1 liter. Over time, brake fluid absorbs moisture from the air, lowering its boiling point, which can lead to reduced performance or even failure during emergency braking. Therefore, I recommend checking it every two years or 30,000 kilometers. When replacing, prioritize the DOT type recommended by the manufacturer, such as DOT4 or DOT5.1. At a repair shop, technicians will use professional tools to drain the old fluid and inject new fluid, ensuring no air bubbles remain in the system, which could compromise safety. The total cost is relatively low—a bottle of new fluid costs just a few dozen yuan—but don’t skimp on quality. DIY is also an option, but be cautious not to damage the system. It’s best to leave it to professionals, as brake issues can lead to serious accidents if mishandled.
