Brake Fluid

Fluids & Filters


Brake fluid is a specially formulated liquid used in the brake hydraulic system. Brake fluid must meet one of three specifications. DOT3 and DOT4 are glycol-based fluids, which absorb water. DOT5 is a silicone-based fluid and does not absorb water. The main difference is that DOT3 and DOT4 absorb water, while DOT5 doesn't. Most cars use DOT 3 fluid from the factory.

Why does your car need brake fluid?

Understanding why your car needs brake fluid is important to understand the importance of changing it. Brake fluid is found in the brake cylinder reservoir, which is used to transfer force into pressure in order to create a braking force. The brake fluid should be maintained between the Add/Min and Full/Max markers on the notch. If the fluid is not maintained, it can lead to brake failure when the fluid begins to boil, putting stress on the brakes and decreasing its functionality. After 3 years, the boiling point of brake fluid is usually below dangerous levels as it will contain a high level of moisture contamination.

What occurs during a brake fluid inspection?

During a brake fluid inspection, your local Master Mechanic will look at the cylinder reservoir to determine which type of brake fluid is required. If you’re unsure if it is time to change your brake fluid, there are three ways which your mechanic can check to determine if it’s contaminated. The first is by using an optical refractometer where a small drop will be placed inside the tester to determine the moisture level and boiling point. The second is by chemical test strips which will change colour depending on the condition. Finally, the third is by using an electronic brake fluid tester to measure the boiling temperature. At Master Mechanic we use (insert brand name/type) because of it’s accuracy.

What are some signs you need it changed?

Brake failure is one of the average driver’s number one fears amongst driving emergencies, so it’s important to know what you can do to prevent this fear from becoming a reality. You should have your brake fluid checked regularly, as we recommend they get checked after a minimum of 1-2 years. While the fluid level gradually drops at a safe level or time, a quick and large drop will show that there is a leak in your brake system. An average driver, who drives 16093.44-24140.16 kilometers a year, uses their brakes 75,000 times a year, meaning that if you wait until after 3 years, the boiling point of the brake fluid is below a safe level.

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