Effective braking is critical in keeping you and others safe on the road. Brake fluid is one essential component of that. In the braking system, it’s what transmits the force from the pedal to your vehicle’s brakes. When that fluid is compromised, however, it could possibly lead to brake failure and your vehicle will fail to stop. To avoid this, you or your mechanic will need to change your car’s brake fluid on a regular schedule (documented in your owner’s manual).
How Much Does a Brake Fluid Change Cost?
- Why You Need to Change Brake Fluid
- Typical Brake Fluid Change Costs
- Signs of Bad Brake Fluid
- Types of Brake Fluid and Their Boiling Points
- Boiling Points and Performance Differences
- What’s the Difference Between a Brake Fluid Change and a Brake Fluid Flush?
Why You Need to Change Brake Fluid
When you press the brake pedal in a vehicle with disc brakes, the braking system’s master cylinder pushes fluid through the brake lines to the brake calipers. The calipers then push the brake pads against the rotor to slow the vehicle.
The hydraulic pressure exerted on brake fluid inherently raises its temperature. This temperature only rises if the brakes are stressed, as might happen when a vehicle is under load or when you’re wringing out a performance car on a track. Were the fluid to boil, it would become ineffective and lead to brake failure. That’s why brake fluid is designed to have a minimum boiling point of 401 degrees Fahrenheit.
However, brake fluid absorbs moisture from the air over time. Moisture can enter the brake system through old or cracked hoses, worn gaskets, or loose connections, and water contamination can lower the brake fluid’s boiling point—sometimes by as much as 30%.
Air bubbles form in the line when brake fluid boils, which can reduce braking effectiveness. Therefore, preventing boiling is critical to keeping the braking system in good working order.
If you’re dealing with a soft or spongy brake pedal, old brake fluid may be to blame.
Also know that water in brake fluid can lead to corrosion of metal components such as the brake lines, the calipers, and parts of the anti-lock braking system (ABS), leaving you with costly repairs, or brake failure in extreme cases.
Typical Brake Fluid Change Costs
The cost of a brake fluid change depends on several factors, including your vehicle's make and model and where you go for service. You should expect to pay between $70 and $120 for the service at an auto repair shop. It may cost more—up to or even more than $250—for luxury-brand vehicles because of their specialized systems and components.
Dealerships tend to charge more than independent shops, but it could be worth servicing your vehicle there if you drive something like a high-performance or luxury vehicle, as the dealership’s mechanics will be familiar with it and likely use branded parts. Then again, independent repair shops can also perform a quality brake-fluid replacement for most vehicles with ease.
If you’re a DIY mechanic, you could try your hand at changing brake fluid, but know that there are risks involved. Incorrect procedures like failing to remove air bubbles or using the wrong type of fluid can impair braking performance and even damage the system. You will, however, likely save some money: a bottle of new brake fluid ranges from $6 to $20.
You’ll also need tools such as a brake bleeding kit, wrenches, a jack, jack stands, and protective gloves, which might amount to a one-time cost of around $60 to $120 if you don’t have them already. That’s a lot more economical than paying $120 every two or three years—which, incidentally, is often the interval for brake-fluid replacement.
Signs of Bad Brake Fluid
There are some surefire ways to tell if your car’s brake fluid is bad. Keep an eye out for:
A spongy or soft brake pedal: One of the first signs of degraded brake fluid is a brake pedal that feels soft or spongy. As we mentioned, moisture can enter a braking system, which lowers the brake fluid’s boiling point and allows air bubbles to form. Air, unlike fluid, compresses easily, which means you’ll lose some of the pressure in the line (hence the soft pedal).
Reduced braking performance: If your vehicle is taking longer to stop, the brakes are slower to respond, or has a long pedal (i.e., where the pedal needs to be pressed closer to floor than usual to slow or stop the vehicle), then have the fluid checked.
Dark, murky fluid: A visual inspection of the brake fluid in the brake fluid reservoir beneath the hood can go a long way. Fresh brake fluid is generally clear to slightly yellow, while dark, murky fluid indicates contamination or aging.
A brake-system warning light: In many vehicles, a brake-system warning light may appear on the dash. If it does, it’s crucial to have someone check the brake fluid reservoir and the brake components ASAP.
Types of Brake Fluid and Their Boiling Points
Brake fluid types can be confusing to understand. Most vehicles use DOT 3, DOT 4, or DOT 5.1 brake fluid, all of which are glycol-based and hygroscopic (water-absorbing). DOT 3 is the most common type of fluid, suitable for most regular vehicles. DOT 4 has a higher boiling point than DOT 3 and is typically used in performance vehicles or those that tow heavy loads. DOT 5.1 goes one step beyond that and would be best for a track car or a vehicle seeing high stress. Check your vehicle’s owner’s manual to determine the correct brake fluid to use.
Boiling Points and Performance Differences
As noted above, brake-fluid boiling points are a critical factor in fluid selection. DOT 4 and DOT 5.1 have a higher boiling point than DOT 3, so they’re a better choice for vehicles that see a lot of heavy braking. This may include those that tow trailers or navigate mountainous terrain. Using the correct type of brake fluid recommended by the vehicle manufacturer is essential to prevent damage to seals, hoses, caliper pistons, and other components.
DOT 5 is a silicone-based fluid that does not absorb water, which can make it more stable in certain conditions. However, DOT 5 is incompatible with most modern braking systems, and primarily used in vintage cars or specific military applications. Mixing DOT 5 with glycol-based fluids (DOT 3, 4, or 5.1) can damage the braking system, so make sure you use the right stuff.
Brake fluids also vary in chemical composition, so mixing different types is usually not advised. Consult your owner’s manual or a trusted mechanic if you’re unsure which fluid to use.
What’s the Difference Between a Brake Fluid Change and a Brake Fluid Flush?
While some people use the terms interchangeably, others make a distinction between a brake fluid change and a brake fluid flush. For the latter group, a brake fluid change involves removing much, but not all, of the old fluid from the system and replacing it with fresh brake fluid. Some of the old fluid remains in areas such as the brake lines and the ABS components.
A brake fluid flush is a more thorough service that completely replaces the old fluid with new. During a flush, all the old fluid is removed, including what’s in the lines, hoses, calipers, and the master cylinder, using a pressure bleeder.
Whether you choose a fluid change or a full flush, both should include brake bleeding, which means the air bubbles are removed as well.
A brake fluid flush can be more expensive, but it’s recommended over a less complete fluid change, as it minimizes potential issues and maximizes your fluid-replacement interval.
