Can You Use Brake Fluid for Power Steering Fluid? Key Facts
If you’ve ever found yourself in a pinch and wondered, “Can I use brake fluid for power steering fluid?” you’re not alone. This question has bewildered many DIY mechanics and car enthusiasts.
In this article, we examine if brake fluid and power steering fluid in cars can be used interchangeably. Let’s begin!
Key takeaways:
- Brake fluid and power steering fluid have different functions, compositions, and viscosities.
- Mixing these fluids can lead to damage, leaks, and reduced performance in your power steering system.
- If the wrong fluid is used, stop driving, consult the manual, flush the system, inspect for damage, and refill with the correct fluid.
- Prevent mix-ups by labeling containers, keeping fluids in original containers, consulting the manual, and organizing your workspace.
- Always use the manufacturer-specified fluid to ensure proper operation and longevity of your car’s systems.

Understanding Brake Fluid and Power Steering Fluid
To determine if brake fluid can be used as power steering fluid, we must first know the functions of each fluid and their importance for a car.
Brake Fluid: The Stopping Power
Brake fluid is a hydraulic fluid used in the braking system of your car. It’s responsible for transferring the force you apply to the brake pedal to the brake calipers or wheel cylinders, ultimately slowing down or stopping your vehicle.
Brake fluid is formulated to handle high temperatures and maintain its viscosity under extreme pressure, ensuring the braking system operates consistently and reliably.
Power Steering Fluid: The Smooth Operator
Conversely, power steering fluid is specifically engineered to facilitate the seamless functioning of your vehicle’s power steering system. This fluid not only serves as a lubricant and coolant for the entire system, but also enhances the longevity of power steering components, ensuring optimal performance and preserving their durability.
The Chemistry: Why Mixing Fluids Is a Bad Idea
Now that we know the functions of brake fluid and power steering fluid let’s discuss the chemical differences between the two.
Different Compositions
Brake fluid and power steering fluid are made up of different chemical compositions. Most brake fluids are glycol-ether based, while power steering fluids are typically mineral oil-based or synthetic.
These distinct chemical properties are designed to meet the specific requirements of their respective systems, and mixing them could lead to disastrous consequences.
Viscosity Matters
Viscosity, or a fluid’s resistance to flow, is another critical factor that differentiates brake fluid from power steering fluid.
Brake fluid is engineered to maintain a consistent viscosity across a wide range of temperatures, ensuring reliable braking performance.
In contrast, power steering fluid has a different viscosity optimized for the smooth operation of the steering system.
The Dangers of Using Brake Fluid as Power Steering Fluid
Now that we’ve established the differences between brake fluid and power steering fluid let’s explore the potential consequences of using the wrong fluid in your power steering system.
Swelling and Deterioration of Seals
Brake fluid, especially glycol-based variants, is known to be incompatible with certain types of rubber used in power steering systems.
When brake fluid comes into contact with these rubber seals, it can cause them to swell and eventually deteriorate. This can lead to leaks, loss of power steering fluid, and ultimately, power steering failure.
Corrosion and Component Damage
Brake fluid’s chemical properties can contribute to corrosion and damage within power steering system components. As a highly hygroscopic substance, brake fluid readily absorbs moisture from the atmosphere. When this moisture infiltrates the power steering system, it can cause metal parts to corrode, leading to early wear and possible system failure.
Reduced System Performance
Utilizing brake fluid as a replacement for power steering fluid could potentially impact the performance of your power steering system.
This is mainly because of the difference in viscosity and lubricating qualities between the two fluids, as brake fluid might not offer sufficient lubrication for the power steering components.
Consequently, this may result in heightened friction, amplified noise, and diminished steering support.
What to Do If You’ve Accidentally Used the Wrong Fluid
If you’ve mistakenly added brake fluid to your power steering reservoir, don’t panic! Here are the steps you should take to rectify the situation:
- Stop driving your vehicle immediately. Continuing to drive with the wrong fluid in your power steering system can cause further damage.
- Consult your owner’s manual or contact your vehicle’s manufacturer. They will provide the appropriate guidance based on your specific make and model.
- Drain and flush the power steering system. You’ll need to remove all traces of the incorrect fluid from the system to prevent further damage. In some cases, this may require professional assistance from a qualified mechanic.
- Inspect the power steering system for damage. Check for any visible signs of leaks or deterioration in the seals and other components. If you notice any issues, consult a professional mechanic for further guidance and repairs if needed.
- Refill the power steering reservoir with the correct fluid. Make sure to use the manufacturer-recommended power steering fluid for your vehicle to ensure optimal performance and system longevity.
Tips for Avoiding Fluid Mix-ups
To prevent accidentally using the wrong fluid in your vehicle, consider following these simple tips:
- Label your fluid containers. Clearly label all automotive fluid containers to avoid confusion when topping off or servicing your vehicle.
- Keep fluids in their original containers. Storing fluids in their original, clearly marked containers can help prevent mix-ups.
- Consult your owner’s manual. Before adding any fluids to your vehicle, double-check your owner’s manual to ensure you’re using the correct type of fluid for each system.
- Stay organized. Keep your garage or workspace organized, with separate areas for different types of automotive fluids.
The Verdict: Stick to the Right Fluid for the Job
In conclusion, using brake fluid as a substitute for power steering fluid is a bad idea. The chemical differences and incompatibilities between the two fluids can lead to damage, leaks, and reduced performance in your power steering system.
It’s always best to use the correct fluid specified by your vehicle’s manufacturer to ensure the longevity and proper operation of your car’s systems.