Picture This: You’re topping up fluids in your car, and by mistake, you pour brake fluid into the power steering reservoir. Maybe you were in a rush, the bottles looked similar, or you just thought, “fluid is fluid.” But that’s not true.
It’s like mixing up salt and sugar in your tea—it completely ruins it. Using the wrong fluid in your power steering system doesn’t just cause problems; it can also lead to costly repairs.
What is Brake Fluid?
Brake fluid is one of the most important fluids in your car. It helps your brakes work properly by creating the pressure needed to stop the vehicle. Without it, pressing the brake pedal wouldn’t slow your car down.
This fluid also keeps parts like the brake pistons, valves, and ABS (antilock braking system) running smoothly. If you ever feel your brakes are slow or not working right, it’s recommended to check the brake fluid first.
What is Power Steering Fluid?
Power steering fluid is another important car fluid that helps you turn the steering wheel easily. It keeps parts like the power steering pump, gearbox, valves, and seals cool and smooth. If the fluid level gets too low, your steering wheel can feel very hard to turn, and sometimes the car may even stall.
Brake fluid and power steering fluid are made for different jobs in your car. Brake fluid is a hydraulic fluid that sits between your brake pedal and the brakes. It’s built to handle very high heat and pressure so your car can stop safely.
Power steering fluid, on the other hand, keeps the steering pump and other steering parts smooth and lubricated. It helps you turn the wheel easily, without feeling like you’re forcing a stuck shopping cart.
Mixing these two fluids may seem harmless, but it can actually cause serious damage to your car.
Power Steering Fluid vs. Brake Fluid
Even though both are car fluids, they are not the same and can’t be swapped.
- Power Steering Fluid: Made from petroleum, mineral oils, and additives. It helps reduce friction, prevents rust, and lets the system handle high heat and pressure.
- Brake Fluid: Usually made from glycol or silicone. There are different types:
- DOT 3: Made with glycol and ether.
- DOT 4: Made with glycol and borate ester.
- DOT 5: Made with silicone.
Both are super important, but each is designed for its own job.
System Compatibility
Brake fluid and power steering fluid can’t be used in place of each other because they are made for different jobs. Power steering fluid works as a lubricant and helps your car steer smoothly. If you put brake fluid in the steering system, it can damage rubber parts.
On the other hand, brake fluid doesn’t have the lubrication needed for steering. If you use it instead of power steering fluid, your steering won’t work properly.
Heat Control
Both fluids can handle high heat, but they work in different ways. Power steering fluid not only transfers pressure but also lubricates metal parts and absorbs heat while keeping the same thickness (viscosity). This helps the steering system run smoothly.
Brake fluid, however, doesn’t need to lubricate parts. Its job is to handle heat and keep the same thickness so your brakes don’t get spongy. Thanks to its high boiling point, brake fluid makes braking safe and reliable.
Here’s Where the Trouble Starts
- Composition: Brake fluid is usually glycol-based, while power steering fluid is a special oil. They are made for different systems and don’t mix.
- Function: Brake fluid handles high heat and pressure in the brake system. Power steering fluid reduces friction and keeps the seals soft in the steering system.
- Impact on Materials: Brake fluid can damage and eat away at rubber seals in the steering system, while power steering fluid is gentle and safe for them.
Simply put, using the wrong fluid in your power steering system is asking for trouble.
Effects of Using Brake Fluid in Power Steering
Putting brake fluid in place of power steering fluid can quickly ruin your steering system. It can damage seals, reduce lubrication, and lead to costly repairs.
- Unusual Noises: If you hear squealing, whining, or moaning sounds when you steer, it could mean the wrong fluid is inside. Brake fluid doesn’t lubricate well and can collect dirt, making the steering noisy.
- Damage to Steering Parts: Brake fluid eats away at rubber seals, hoses, and gaskets. Over time, this can cause leaks, stiffness, or even total pump failure.
- Fluid Appearance and Smell: When brake fluid mixes with power steering fluid, the fluid may look cloudy and give off a sharp, chemical odor. This is a clear sign that the wrong fluid is in the system.
- Leaks: Bad seals often lead to leaks. With less fluid, the steering wears out faster, and controlling the car becomes harder.
- Other Warning Signs: You may notice the steering feels heavier, the wheels feel shaky, or a steering warning light might turn on your dashboard.
Accidentally Put Brake Fluid in Power Steering? Here’s What to Do
Act fast — the sooner you fix it, the less damage it will cause.
- Don’t start the engine. If you run the car, the brake fluid will spread through the steering system and cause more damage.
- Drain the reservoir. Use a syringe or turkey baster to remove as much of the wrong fluid as possible.
- Flush the system. This clears out any leftover brake fluid. A mechanic has the right tools to do a full flush.
- Refill with the right fluid. Always use the recommended power steering fluid for your car.
Clear Signs Your Power Steering Fluid Is Contaminated
Watch out for these warning signs that the wrong fluid might be in your power steering system:
- Fluid looks darker than normal or has a milky appearance
- Strong, chemical-like smell coming from the reservoir
- Strange noises (whining or squealing) when turning the wheel
- Steering feels stiff or less smooth than usual
- Small puddles of fluid under your car near the steering parts
If you notice any of these signs, it’s important to act quickly before the problem gets worse.
Also Read: Which Brake Fluid is Best for My Car: DOT 3, DOT 4, or DOT 5?
What Happens If You Put Power Steering Fluid in Brake Fluid?
If you accidentally pour power steering fluid into the brake fluid tank, it can seriously damage your brakes. The rubber seals inside the brake system start to swell because of the wrong fluid, which blocks the brake lines.
For example, in the master cylinder, swollen seals can block the return ports. This means the fluid can’t flow back when you release the brake pedal. Since brake fluid expands with heat, the brakes may stay engaged, causing the wheels to lock.
At first, you might notice spongy brake pedals, which is an early sign of brake failure. If not fixed, the rubber parts can get completely ruined, leading to total brake system failure.
Also Read: Which Fluids Are Safe (and Unsafe) Alternatives to Brake Fluid?
What to Do If You Put Brake Fluid in the Power Steering System
If you accidentally add brake fluid instead of power steering fluid, you need to drain it right away. Leaving it in the system can cause serious damage. Follow these steps:
- Do not start the engine or use the brakes. This keeps the brake fluid from spreading through the steering system.
- Open the power steering reservoir and remove as much fluid as you can using a syringe or turkey baster.
- Jack up your car and slowly turn the steering wheel left and right. This will push more of the fluid into the reservoir. Keep draining as it comes up.
- Flush the system. Add fresh power steering fluid, then drain it again. Repeat this process a few times to remove all traces of brake fluid.
- Lower the car and fill the reservoir with new power steering fluid.
Now your system should be safe to use again.
Preventive Measures
Follow these simple steps to avoid mixing up brake fluid and power steering fluid:
- Label your bottles: Clearly mark each container so you don’t get confused.
- Store them separately: Keep them in different spots to prevent mistakes.
- Read before you pour: Always double-check the label before adding any fluid to your car.
- Regular maintenance: Have your steering fluid checked during routine services to catch problems early.
- Ask for help: If you’re not sure which fluid to use, let a mechanic handle it.
These small habits can save you from costly repairs and keep your car running smoothly.
Final Thoughts
Pouring brake fluid into the power steering system isn’t a small mistake—it can damage the pump, hoses, seals, and lead to expensive repairs. The wrong fluid causes problems fast, so quick action and prevention are key.
Think of your car fluids like ingredients in a recipe: put the right one in the right place, and everything works perfectly. Use the wrong one, and the whole system can fail. Protect your car’s performance and avoid costly damage by always using high-quality, manufacturer-recommended products from Fubex Lubricants — your trusted partner in automotive care.
FAQs
Q1: What can I use instead of power steering fluid?
In some older cars, power steering fluid and transmission fluid were used the same way because both are hydraulic fluids. If your power steering fluid is low, you can use automatic transmission fluid (ATF) as a temporary fix. But in modern cars, it’s recommended to only use the fluid listed in your owner’s manual.
Q2: Can you mix power steering fluid and brake fluid?
No, you can’t mix them. These two fluids are made from different materials and have different jobs. Mixing them can damage parts of your car, even though both are meant to keep systems working smoothly.
Q3: Can transmission fluid be used as brake fluid?
No, you should never use transmission fluid as brake fluid. It can cause overheating, poor braking, and even complete brake failure.
Editor-at-Large
A passionate writer in the lubricant industry, Awais Iqbal has been covering oils, greases, and industrial fluids since the start of his career. At 25, he’s already written for blogs, catalogs, and brand guides across the UAE. Awais’s insights help companies connect with their audience, and his clear, helpful writing style is trusted by brands in the region.
