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Brake Fluid 101: Everything You Need To Know About Brake Fluid

brake system - fluidMost vehicle owners are aware that changing the vehicle’s engine oil is one of the most important maintenance services your vehicle needs. While it’s true, and oil does protect your engine from disastrous situations, there are many fluids in your vehicle that serve a very important purpose and keep your vehicle functioning optimally. This includes everything from power steering fluids, coolant, transmission fluid, and brake fluid. Brake fluid is necessary because, without it, you wouldn’t be able to stop your car. Most vehicles today are equipped with hydraulic brake systems, which require fluid to build up pressure and eventually stop your vehicle. Over time though, just like used oil, it begins to break down making its impact lest effective. Here’s everything you need to know about brake fluid and why a brake fluid flush is necessary for your vehicle.

Brake fluid is an integral part of the hydraulic brake system. Brake pressure forces fluid to the brakes, causing the pads to clamp down on the rotors, attached to the wheel hubs that spin as the wheel turns. The high pressure causes the car to slow down. Without any brake fluid, no pressure can be created to stop the car. Brake systems are completely sealed to assist in creating pressure. If there is a leak in the system, and the vehicle is losing brake fluid, your brakes will not be able to function well, or at all. Brake fluid leaks can be very dangerous and for safety’s sake, it’s best to avoid driving the vehicle until a professional can fully inspect the system. 

How the Brake System Works

  1. The driver presses down on the brake pedal, connected to the master cylinder that contains fluid.
  2. Once the pedal comes down, it compresses a piston in the brake caliper at each wheel.
  3. The compression from the piston multiplies the pressure greatly, within the brake lines, sending brake fluid into motion.
  4. Pressure from the hydraulic fluid aka brake fluid causes the brake pads to clamp down on the rotors, making contact with the wheels to slow and stop the rotation.


Brake fluid is hydroscopic which means it absorbs moisture from the air. Water in the system can be troublesome, causing the fluid to degrade. Additionally, water has a much lower boiling point than brake fluid. Because there is a tremendous amount of heat created while braking, boiling water in the brake lines can cause your brakes to quit working altogether. That’s why having a brake fluid flush performed regularly is so important. Removing all of the old, contaminated fluid and replacing it with fresh, clean fluid will help to ensure your brakes continue to function properly.

Over time and daily use, components within the braking system begin to deteriorate. Pieces of rubber and other bits of debris flake off and wind up in the brake fluid. With this build-up of debris, paired with the added moisture absorbed from the air, your brake fluid is less likely to be able to perform its job. You know that engine oil is the lifeblood of your engine and you wouldn’t avoid changing it regularly. The same could be said for brake fluid. When brake fluid gets dirty and contaminated, your brake performance is affected. When it comes to driving–and stopping for that matter, you want to be able to rely on your brakes and have them respond when you need them most. 

How Often to Flush Brake Fluid

Brake systems are completely sealed and with so many components including the brake pedal, reservoir, brake lines, cylinders, pistons, and brake fluid, at some point damage can occur that may cause brake fluid leaks which will greatly affect brake performance. While an inspection of your brake system should be performed at every oil change to check for wear or leaks, a brake flush should be completed every 30,000 miles. Keep in mind that a brake flush differs from a brake bleed. A brake flush removes all fluid from the system via a vacuum and replaces the system with clean fluid. A brake bleed only removes enough brake fluid to remove any air bubbles out of the brake lines. 

A soft brake pedal or any sudden changes in braking is an indication that a leak has occurred. In these situations, it’s best to pull over and check the brake fluid level in the reservoir. Any level under three-quarters full should be concerning. Because the system is sealed, the fluid should remain nearly full, however, some fluid loss is normal with regular use. If you are concerned that a brake fluid leak is present, have your vehicle towed to an auto repair center for an immediate inspection. Do not risk your safety or the safety of others by attempting to drive with brakes that could be compromised.  

How Much Is A Brake Fluid Flush, Anyway?

Brake fluid flushes can range anywhere between $90 – $150. However, cost varies based on vehicle make, model, and engine type. To find out how much a brake fluid flush for your vehicle is, reach out to a knowledgeable and friendly Service Advisor at any of our Sun Devil Auto locations. Not only can our Service Advisors provide pricing for maintenance services on your car, they can also answer any questions you may have as well as help you develop a maintenance plan for your vehicle. Sun Devil Auto is your partner for all things automotive related. Give us a call today!