Blog Car Care Advice Why You Need a Brake Fluid Flush (+ 4 Symptoms and Costs)
Car Care Advice

Why You Need a Brake Fluid Flush (+ 4 Symptoms and Costs)

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A brake fluid flush is a procedure that removes old fluid from your brake system and replaces it with fresh brake fluid. 

But why is it necessary?
And how to tell that it’s time for a brake fluid flush?

In this article, we’ll cover what a brake fluid flush is, how often you’ll need it, and how much it will cost. We’ll also highlight the most convenient way to get a brake flush done.

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Let’s jump right in.

What Is A Brake Fluid Flush?

A brake fluid flush involves draining out contaminated or old fluid from your brake system and replacing it with clean and new fluid. Flushing helps maintain the health and effectiveness of your vehicle’s brakes.

But what does brake fluid do?

Brake fluid amplifies and transmits the force you apply when you press down on the brake pedal. 

When you engage the brake pedal, that force activates the brake master cylinder. In turn, the master cylinder forces the brake fluid along the brake line to reach the brakes at each wheel.

If your car uses a disc brake system, a plunger inside the master cylinder pushes pressurized fluid into the brake caliper pistons. These hydraulic pistons then squeeze the brake pad against the wheel rotor to create friction. And this frictional force helps stop the car.

On the other hand, in a drum brakes assembly, pressurized brake fluid acts on the wheel cylinder that pushes a set of brake shoes against drums to stop your wheels.

Irrespective of whether you use drum brakes or disc brakes, there are two kinds of brake fluid flushes:

Now that you understand what a brake fluid flush is, let’s go over why it’s so critical for brake performance.

Why A Brake Fluid Flush Is Necessary

Your brake system comprises several working parts. 

Many of these parts are linked together using brake lines and hoses, which use brake fluid to transmit and amplify forces. That’s why it’s essential to ensure that the brake fluid retains its quality and doesn’t hamper the functioning of your other brake components.

And this is where a brake fluid flush comes in. It helps you:

1. Maintain The Quality Of The Brake Fluid

As brake fluid ages with repeated use, chances are that it will get contaminated with material from different parts of the brake system, like:

When this happens, it can limit the pressure transmitting capacity of this hydraulic fluid and reduce your stopping power. Ultimately, as the contamination gets excessive, your hydraulic brake system could go out of service.

Moreover, the additive package in your brake fluid gets depleted over time. 

What’s that?

The additive package combines corrosion inhibitors, anti-rust compounds, and pH balancers into the brake fluid stored inside your master cylinder. This prevents the fluid from corroding your car’s parts.

Once the additive package level drops, corrosion can build up in the internal brake system and compromise brake functioning.

Carrying out a brake fluid flush replaces the bad brake fluid in the master cylinder reservoir with fresh brake fluid. The new fluid helps restore additive package levels, remove contaminants, and ultimately improve brake performance.

2. Prevent Moisture Build Up

Brake fluids are hygroscopic, meaning they tend to absorb moisture.

As the brake fluid comes in contact with several brake system components, moisture content can affect their functioning.


The moisture absorbed by the brake fluid can lead to the corrosion of several brake parts (like the brake caliper, brake master cylinder, or brake rotors) since many of them are made of metal. And this corrosion can disrupt the functioning of your braking system.

Performing a brake fluid flush eliminates the moisture-laden fluid by using fresh brake fluid in its place to prevent corrosion and ensure the optimal health of a brake system component.

This is especially important when it comes to the ABS and other traction control components.
The ABS (Anti-lock Braking System) and traction control components are hyper-sensitive to moisture. If these components are exposed to contaminants from the old brake fluid for long periods, they could get damaged, leading to brake failure and costly brake repair

Flushing the brake system regularly to add clean brake fluid can protect a brake system component from degradation by keeping moisture and debris at bay.

It’s clear that brake fluid flushes are very helpful, but how do you know when your vehicle needs a brake fluid flush service?

4 Symptoms That Indicate That You Need A Brake Fluid Flush

Here are some signs that indicate that you might need a brake fluid change:

1. Leaky Brake Fluid

If you notice a brake fluid leak, you could require an immediate brake fluid flush.

A brake fluid leak reduces the braking force transmitted through the brake line.

To confirm your brake fluid level, you can look at the brake fluid reservoir. Typically, you will find the brake fluid reservoir near the engine compartment. You can refer to your car owner’s manual to find the exact location.

However, if you don’t feel confident about confirming a brake fluid leak on your own, you can reach out to an expert mechanic for help. They can come to your driveway, evaluate the brake fluid level, and carry out a brake fluid flush or a brake maintenance service if needed.

2. Contaminated Brake Fluid

Clean brake fluid looks somewhat golden, light brown, amber, or clear. If the brake fluid is much darker or dirtier, you might need a brake fluid flush soon enough.

This can happen due to excessive brake fluid aging or contamination from rubber, rust, or other debris that gets clogged in the brake line.

If this is the case, take your car to an auto repair shop or have a qualified mechanic come over to perform a quick brake fluid flush service and get your brake system back in perfect condition.

3. Brake Pedal Feels Soft

At times when you’re applying brakes, you might feel that your brake pedal is spongy

If brake fluid absorbs too much moisture, air pockets containing water vapor are created when these fluids get exposed to high temperatures. And these air pockets reduce the effectiveness of your vehicle’s brakes and lead to a soft-feeling brake pedal.

When this happens, your brakes won’t respond as you want them to and may cause potential brake failure, leading to significant safety hazards.

If you notice a spongy pedal, request a brake system inspection immediately. An experienced mechanic can then flush your vehicle’s brake fluid to remove any moisture in the brake line and add moisture-free, fresh fluid.

4. The ABS Light Turns On

In some cars, the ABS warning light on the dashboard gets activated when you need a brake flush. This doesn’t mean the ABS light turns on only if you have bad brake fluid or a low brake fluid level. 

An illuminated ABS light can also result from:

To be safe, when the ABS light turns ON, consider getting your vehicle inspected by a professional mechanic to diagnose and fix the underlying issues.

Next, let’s find out how frequently you should flush your brake fluid.

How Often Do You Need A Brake Fluid Flush?

There’s no hard and fast rule regarding how often you’ll need fluid flushes.

Generally, most professional mechanics would recommend that you perform a brake fluid exchange every 30,000 miles or 2 years. This should help you overcome most of the after-effects of aging and bad brake fluid.

You can also check your vehicle owner’s manual for a more specific estimate of how often you’d need a brake flush. 

However, your timeline for flushing the vehicle’s brake fluid can accelerate if you regularly use the vehicle’s brakes aggressively, such as in stop-and-go traffic. 

Tip: When you’re brakes are being flushed for new brake fluid, consider getting a tire rotation, since your mechanic is already working with your wheels. Also, have your brake fluid levels checked during an oil change service.

But what’s the cost of a brake fluid flush? 
Let’s find out.

How Much Does A Brake Fluid Flush Cost?

The costs of performing a brake fluid flush can range between $90 and $200.

It usually depends on your choice of new brake fluid and the auto repair labor costs in your area. Moreover, it can also depend on your vehicle’s year, model, engine, and make.

Hot Tip: The best brake fluids have a relatively high boiling point as they need to withstand the high amount of heat generated during braking. The commonly used DOT 4 glycol-based brake fluid has a boiling point of 155°C and costs $6 – $39 per quart. 

For an accurate estimate of the brake fluid change cost for your vehicle, just fill out this online form.

Now that we know how much a brake fluid flush costs, let’s check out how it’s done. 

What Happens During A Brake Fluid Flush?

For best results, it’s recommended that you take your vehicle to an auto service shop or request a mobile mechanic to come over to your location for brake service.

During a brake fluid flush, your mechanic would:

1. Locate the brake fluid reservoir.

2. Drain out the contaminated and old brake fluid.

3. Clean out any debris left in the braking system.

4. Check whether any other brake components, like a brake caliper, brake master cylinder, brake pad, or brake rotors, will need to be replaced.

5. Carry out brake fluid replacement with high-quality, fresh fluid.

6. Remove any air trapped in the brake lines using a bleeder.

7. Verify that the brake system is working correctly.

Luckily, there’s an easy way to find a certified mechanic to perform such a brake fluid replacement:

The Easiest Way To Flush Your Brake Fluid 

The most convenient way to flush brake fluid is to have a mobile mechanic visit you and do the brake service right then and there.

And for a mobile auto service, AutoNation Mobile Service is your best bet!

AutoNation Mobile Service is a mobile vehicle repair and maintenance solution that offers these benefits:

Final Thoughts

A brake fluid flush helps you replace aged or contaminated brake fluid to maintain brake performance and prevent corrosion from creeping in.

Fortunately, carrying out a brake fluid flush for your vehicle is super convenient with AutoNation Mobile Service. Just book your brake maintenance service online, and our mobile mechanics will come to you, ready to perform a proper brake fluid flush service.