Power Steering Fluid in Brake Reservoir: 5 Easy Steps to Fix

Have you mistakenly added power steering fluid to your brake reservoir? Don’t panic, it’s a common error. 

Although these fluids are not interchangeable and mixing them can cause serious damage to your car’s braking system, there’s a solution to this problem. 

Here are five easy steps to fix this issue and prevent potential harm to your vehicle. 

Understanding the Problem

To comprehend the issue at hand, it’s crucial to understand the roles of power steering fluid and brake fluid in your vehicle. 

Power steering fluid is a type of hydraulic fluid that helps transfer power in your vehicle’s steering. 

It allows for smooth and effortless turning of the steering wheel, providing an easier driving experience. 

On the other hand, brake fluid is also a type of hydraulic fluid designed to withstand higher temperatures and to not compress, allowing it to effectively transfer the force from the brake pedal to the brake rotors.

Mixing these two fluids can lead to disastrous consequences. The problem arises from the fact that power steering fluid is not engineered to withstand the kind of heat and pressure that brake fluid can handle. 

Potential Damage Caused by Mixing Fluids

Mixing power steering fluid with brake fluid can cause several problems, some severe enough to leave your car undriveable. Here are the key issues:

  1. Corrosion of Brake Parts: Brake fluids are designed to protect the braking system’s metal parts from corrosion. Power steering fluid lacks these protective elements and can cause the metal components to corrode, affecting braking efficiency.
  2. Degradation of Rubber Seals: The rubber seals within the brake system are not compatible with power steering fluid. The interaction can lead to the degradation and possible failure of these seals, causing leaks and air infiltration.
  3. Reduced Braking Power: With power steering fluid in the mix, the overall viscosity of the brake fluid is altered. This can lead to decreased hydraulic pressure, compromising braking power and potentially causing brake failure.
  4. Damage to ABS Module: The ABS (Anti-lock Braking System) module, a crucial part of maintaining control during hard braking, can be damaged by the foreign fluid, leading to expensive repairs or replacements.
  5. Overheating and Boiling: Brake fluid has a higher boiling point than power steering fluid. Mixing the two can lead to a reduced boiling point, causing the fluid to boil during intense braking. This results in brake fading or even complete brake failure.

Signs of Contamination

Recognizing the signs of contamination due to mixing power steering fluid with brake fluid is crucial for maintaining the safety and functionality of your vehicle. 

Here are some of the most common indications that there might be power steering fluid in your brake reservoir:

  1. Decreased Brake Performance: One of the earliest signs of contamination is a noticeable decrease in brake performance. This could present as longer stopping distances or the need to apply more force to the brake pedal than usual. If you notice these signs, it’s important to investigate immediately as they indicate a serious safety issue.
  2. Unusual Noises: Squeaking or grinding noises when braking could also signify contamination. This is usually due to the corrosion of brake parts caused by the absence of protective elements in the power steering fluid.
  3. Leaking Fluid: Degraded rubber seals might result in visible leaks underneath your car. These leaks could lead to a drop in hydraulic pressure, further affecting brake performance.
  4. Warning Lights: Most modern cars have a warning light that will illuminate if the brake fluid level drops below a certain point or if the ABS module detects a problem. If your brake warning light comes on, it should not be ignored as it could be a sign of contamination.
  5. Pedal Feel: Changes in the brake pedal feel, such as becoming “spongy” or easy to push down, could indicate that the brake fluid has been contaminated.

It’s essential to act promptly if you notice any of these signs. Ignoring them can result in dangerous driving conditions and costly repairs. 

Unless Always consult with a professional mechanic if you suspect that your brake fluid may be contaminated.

Safety Precautions

Before attempting any DIY fixes, it’s crucial to prioritize safety above anything else. Here are some important safety measures that you should take:

Personal Protective Equipment (PPE)

Safety begins with wearing appropriate Personal Protective Equipment (PPE). This ensures you are protected from potential dangers during the repair process. 

At a minimum, PPE should include protective gloves to prevent any harmful substances from coming into contact with your skin, safety glasses to shield your eyes from potential fluid splashes, and durable footwear to protect your feet from any falling objects. 

In some instances, you may also need a face mask or respirator, especially when working with chemicals or in a dusty environment.

Working in a Well-Ventilated Area

When working with automotive fluids, it’s critical to operate in a well-ventilated area. Some brake and power steering fluids can emit fumes that are harmful if inhaled. 

A well-ventilated workspace ensures that these fumes are dispersed, reducing your exposure to potential hazards. 

This not only safeguards your health but also enhances your comfort, allowing you to focus on the task at hand.

Remember, safety should be your main concern when attempting any vehicle repairs. Never compromise on these precautions, even if the repair seems minor. If you are unsure about any process, always consult a professional mechanic.

Tools and Materials Needed 

In order to safely and correctly fix your vehicle’s brake system, it’s essential to have the proper tools and materials on hand. Here is a list of items you would typically need:

Brake Fluid

  • It’s crucial to have a new, unopened bottle of brake fluid that is compatible with your vehicle’s specifications. 
  • Brake fluid is hygroscopic, meaning it absorbs moisture from the air, so always ensure that the bottle is sealed before use.

Turkey Baster

  • A turkey baster is a handy tool for removing the old brake fluid from the reservoir. 
  • It’s simple to use and removes the need for any disassembly of the brake system, making the process cleaner and more efficient.


  • A container is required to collect the old brake fluid. 
  • Since brake fluid is toxic and damaging to the environment, it’s important to collect and dispose of it responsibly. 
  • The container should be clean, free from any contaminants, and have a tight-fitting lid to prevent spills.


  • A good-quality wrench is needed to loosen and tighten the bleed screw on the brake caliper. 
  • This allows the old fluid to be expelled and the new fluid to be added. 
  • Ensure the wrench fits the bleed screw perfectly to avoid stripping it.

Lint-Free Cloths

Lastly, you’ll need lint-free cloths for cleaning up any spills and wiping down parts. Brake fluid is highly corrosive and can damage painted surfaces, so immediate clean-up of any spills is essential. 

Having these tools and materials readily available before you begin will ensure a smooth, efficient, and safe repair process.

Step-by-Step To Fix

Here’s a simple guide to help you fix contaminated brake fluid:

Step 1: Draining the Contaminated Fluid

  • Using the turkey baster, carefully suck out as much of the old, contaminated brake fluid from the reservoir as possible. 
  • Then, deposit this fluid into your designated container.

Step 2: Cleaning the Brake Reservoir

  • Once you’ve removed as much fluid as possible, it’s time to clean the brake reservoir.
  • Using a lint-free cloth, carefully wipe away any remaining fluid or debris. 
  • Be thorough to ensure all contaminants are removed.

Step 3: Refilling with the Correct Brake Fluid

  • Now, open your new bottle of brake fluid and carefully pour it into the reservoir until it reaches the indicated level. 
  • Remember, always use the correct type of brake fluid specified for your vehicle.

Step 4: Bleeding the Brake System

  • To ensure the new fluid reaches the entire brake system, you must bleed the brakes.
  • Using your wrench, slightly loosen the bleed screw on the brake caliper and let the fluid flow out (into your container) until you see the new, clear fluid. 
  • Repeat this process for all wheels. 

Step 5: Testing the Brakes for Proper Functionality

  • After you’ve bled the brake system and topped off the brake fluid, it’s time to test your brakes. Start your vehicle and press the brake pedal. 
  • It should feel firm and responsive. 
  • If it feels soft or sinks to the floor, there may still be air in the brake system. 
  • In this case, bleed the brakes again until the pedal feels firm.

Troubleshooting Common Challenges

Dealing with vehicle maintenance, especially with brake fluid contamination, is bound to present certain challenges. 

Let’s delve into some common issues that might crop up during the process, and provide effective solutions to overcome them. 

Challenge 1: Brake Pedal Still Feels Soft

Even after draining the contaminated fluid, cleaning the reservoir, refilling with fresh fluid, and bleeding the brakes, you might find the brake pedal still feels soft or sinks to the floor. This could be a sign of lingering air in the brake system. 

Solution: In this situation, you should repeat the brake bleeding process. Make sure to start from the wheel farthest from the master cylinder and work your way closer. 

Challenge 2: Difficulty Loosening the Bleed Screw

Sometimes, due to rust or prolonged exposure to elements, the bleed screw on the brake caliper may become difficult to loosen. 

Solution: Apply some penetrating oil to the screw and let it sit for a few minutes before attempting to loosen it again using your wrench. 

If it’s still stuck, you might need to use a screw extractor or seek professional help. 

Challenge 3: Brake Fluid Leaks

If you notice brake fluid leaking from the system even when the vehicle isn’t running, you might have a leaky brake line or brake master cylinder.

Solution: Inspect the brake lines and master cylinder for signs of leakage. If you find a leak, it’s critical to have it repaired immediately. 

This task can be complex, so it’s recommended to seek professional help if you’re unfamiliar with the process. 

Remember, safety is paramount. Always refer to your vehicle’s owner’s manual for specific instructions related to your vehicle model, and if unsure, seek professional assistance.

When to Seek Professional Help

There are several scenarios where it is highly recommended to seek the help of a professional mechanic instead of attempting a do-it-yourself solution. 

1. Complex Repairs: If you’re dealing with a complex repair, such as a transmission rebuild, it’s safer to leave this to professionals. These types of tasks require specific knowledge and tools that the average DIY enthusiast might not have. 

2. Lack of Confidence: If you’re not confident in your ability to perform a repair, it’s better to seek professional help. Confidence is a significant part of successful DIY repair, and if you’re unsure, you’re more likely to make mistakes.

3. Lack of Time: If you’re pressed for time, a professional repair shop can carry out tasks more quickly due to their experience, specialized tools and multiple personnel.

4. Warranty Concerns: If your vehicle is under warranty, performing certain repairs on your own may void this warranty. Always check your vehicle’s warranty terms before conducting a DIY repair.

In all the above instances, prioritizing your safety and that of your vehicle is significantly important. 

It’s not worth taking a risk that could endanger you or result in more costly repairs down the line. Remember, the welfare of you and your vehicle always outpaces the potential savings of a DIY repair.

Tips to Avoid Filling Brake Reservoir with Power Steering Fluid

Mistakes can happen, but when it comes to your vehicle’s maintenance, some errors can cause significant damage. 

One such blunder is accidentally putting power steering fluid in the brake reservoir. Here are some tips to avoid this common mistake:

  1. Label Your Containers: Clearly label your fluid containers. This simple act can prevent confusion and accidental mix-ups.
  2. Separate Storage: Store your power steering fluid and brake fluid in different areas. This separation reduces the chances of you picking up the wrong container.
  3. Double-check: Always double-check the labels before pouring the fluid. This step is crucial, especially if the containers are similar in appearance.
  4. Understand Your Vehicle: Familiarize yourself with your vehicle’s fluid reservoirs. Knowing where each specific fluid goes can help you avoid errors.
  5. Ask for Help: If you’re unsure, don’t hesitate to seek professional assistance. It’s always better to be safe than sorry.

Remember, your vehicle’s health is paramount, and taking a little extra time to ensure you’re adding the right fluid in the right reservoir can save you from costly repairs later.


In conclusion, the health of your vehicle is not something to be taken lightly. Mistakes such as mistakenly filling your brake reservoir with power steering fluid can lead to significant damage and costly repairs. 

Therefore, it’s pivotal to label your containers, separate and store them properly, double-check before use, understand your vehicle’s reservoirs, and never hesitate to ask for professional help when in doubt. 

Remember, safety is paramount, and a small extra effort in maintenance can save you a lot of trouble in the long run. We hope these tips will help you avoid common maintenance mistakes and keep your vehicle in optimal condition. 

Please feel free to share your experiences or any questions you might have in the comments section below. Your input could help another reader avoid a costly error.

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