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How to Check Your Car's Brake Fluid

Anup Patwardhan
The braking system is one of the most crucial systems in a car. The brake fluid plays a vital role in ensuring that the brakes function properly on application. Naturally, as a car owner, to maintain brake fluid in the braking system, you should know how to check the brake fluid level in your car. This story shall tell you how.

Did You Know?

When you slam the brakes on your car, the average temperature of the rotors in the braking system can exceed 300ºC, while in case of an F1 race car, it can spike up to 1000ºC!
The braking system or mechanism is an essential part of your car. Brakes are 'B' in the 'ABC' of driving, with the other two being an 'A'ccelerator and a 'C'lutch. Almost all automobiles, today, come equipped with hydraulic brakes which use a hydraulic fluid to stop wheel rotation.
When you press the brake pedal, the brake fluid, through the master cylinder and a series of pipes, forces the brake pads to stop the rotor attached to the rotating wheel. Along with braking, the brake fluid also serves as a lubricant for the moving parts in the braking system.
There are various types of brake fluids available on the market, and the Society of Automotive Engineers (SAE) and the Department of Transportation (DoT) have designated various grades and standards for brake fluids.
There are two major types of brake fluids. These are silicone-based brake fluids (for example - Dot 5) and glycol-based brake fluids (for example - Dot 3, Dot 4).

How to Check the Brake Fluid?

  • Pop the hood of the car. Ensure that the engine is cold before probing any further.
  • Locate the brake fluid reservoir, which is generally located at the back of the engine bay, on the driver's side.
  • Check the level of the brake fluid in the reservoir. The reservoir, usually transparent, will have 'Max' and 'Min' markings present on it. At times, instead of 'Min', it may be marked as 'Add'.
  • If the level of the fluid is below the 'Min' or 'Add' mark, then you need to add brake fluid in the reservoir.
  • Brake fluid also needs to be changed if it is not colorless or has changed its color.
  • When replacing the fluid, remember to wipe any spilled fluid as it is very corrosive as well as toxic.
  • Once done, close the reservoir as well as the hood of the car.
The color of the fluid can change from being colorless over time due to the addition of impurities; however, this is not the same in the case of DoT 5 silicone-based brake fluid, which is purple in color.
Impurities lower the boiling point of the fluid, which makes it ineffective at dissipating the heat generated due to the applying of brakes. One can use brake fluid test strips to detect the level of the wear of corrosion inhibitors in the fluid.
Check the brake fluid regularly, typically once in a month or two. Usually, the need to change the brake fluid arises after a couple of years, or after your car has clocked 30,000 miles. In case the brakes feel spongy, in spite of the reservoir containing sufficient brake fluid, take the vehicle to an auto mechanic to get the issue diagnosed immediately.