If you stop and think about it, there are a lot of different fluids in your vehicle. There’s gasoline or diesel, coolant, transmission fluid, oil, brake fluid, windshield wiper fluid, and power steering fluid. Are any of them interchangeable? Have you ever asked, “can I use brake fluid for power steering fluid?” What would happen, and would it damage the vehicle?

Unfortunately, brake fluid and power steering fluid are not interchangeable. You can’t use brake fluid in place of power steering fluid and vice versa. It would cause significant damage, including swollen or busted rubber seals, leakage, or breaking down the power steering altogether.

There are some vehicles out there that use the same fluid for the transmission and power steering, with those two being interchangeable if necessary. However, you should always exercise caution and check the vehicle manual before doing any fluid swap.

What is the difference between brake fluid and power steering fluid?

man changing power steering fluid on car

The first difference that you will notice between the two fluids is the color. Brake fluid is almost always a light brown or tan-colored liquid that is reasonably clear. Of course, the two fluids lubricate two radically different systems, so it makes sense that one couldn’t be used in place of the other.

Brake fluid

Brake fluid is part of a hydraulic-based brake system. Brake fluid is glycol-based, and its primary function is to increase the pressure you apply with your foot when you step on the brake. It does this through pressure. Imagine a balloon full of air. When you squeeze the balloon, the pressure of the air inside bulges the walls of the balloon outward.

If a vehicle didn’t utilize any sort of brake fluid, it would take an enormous amount of pressure placed on the brake pedal to force the brake pads into action. In fact, it would take too much pressure, and it wouldn’t be considered safe with the weight and speed of cars being what they are.

Brake fluid is an adjustable viscosity. That means that its thickness as a fluid remains the same no matter how hot or cold it gets. When the brake pad presses against the disc and the car is traveling at a decent speed, the heat generated from the friction is immense.

Brake fluid is designed to withstand that heat and continue to function at the same viscosity. It has an extremely high boiling point, and it would take something wrong with the vehicle to make it reach that temperature.

Pros Cons
Provides excellent pressure
Highly corrosive and caustic
Decent lubricant Not very long-lasting
Prevents corrosion in the brake system Low compressibility rating
Ages slowly

Power steering fluid

If you’re old enough to remember the days before power steering, you understand what the addition of power steering brought to the table. Thanks to power steering and the fluid that goes into it, you can turn the wheel easily, rather than muscling the vehicle into turns.

Unlike brake fluid that’s under pressure through a vacuum booster and the fluid’s ability to maintain viscosity, power steering fluid operates through a motor. The power steering motor is located directly behind the steering column, well within the confines of the dashboard.

The steering wheel itself is set into place on top of a series of gears, all interlocking and operating as a single unit. There is also a control module, steering sensors, and the steering motor. All of them operate in sync with one another. There are two types of power steering technologies as well.

The first is hydraulic power steering, and the second is electronic power steering. Both types require the use of power steering fluid. The fluid is not just a lubricant. It's also pressurized. When you turn the wheel, this pressurized fluid assists by pressing the gears into the rotation, making your job easier.

Like brake fluid, power steering fluid is stored in a reservoir, where it is then pumped out to where it needs to be when used. Power steering lasts a long time and can go well into high mileage territory.

Pros Cons
Non-corrosive Ages to a brownish-black
High level of compressibility
Excellent lubricant

What happens if brake fluid gets into the power steering system?

If it is a small amount, there might not be any immediate effects but, in time, you will start to notice various symptoms. Brake fluid is a completely different kind of fluid from power steering, and it has no place in a power steering system.

  • The steering column may emit a foul smell
  • The system will degrade and eventually become untenable
  • The power steering system will lose its lubrication
  • It will dissolve paint on anything it touches, especially if it leaks out

The severity of the problem is determined by how much brake fluid went into the power steering reservoir. Even a small amount can eventually cause significant problems if you don’t have the system completely purged.

How to get brake fluid out of your power steering system

bottle of brake fluid standing on top of car engine

If you accidentally placed brake fluid in the power steering reservoir, don’t panic just yet. You can get it out of the reservoir without the brake fluid having an opportunity to mess up your power steering system.

However, the moment you fire up the vehicle for the first time, it's too late for easy, uncomplicated measures, as you will have to flush the entire system to get the brake fluid completely out.

In most vehicles, the reservoir is detachable. It may be a bit of a pain in the neck to get the reservoir out, but it is usually a matter of locating the ingress and egress tubes and disconnecting them. Sometimes, these tubes snap into the reservoir, and sometimes they will have O-ring clamps on them.

Either way, detach the tubes and try to work your fingers down to the bottom so you can plug the exit hole as you pull the tank out. This will stop power steering and brake fluid from pouring all over everything in your engine compartment.

Dump all of the liquid into a safe container and thoroughly wash the container with hot water and a mild detergent. The goal is to get every bit of brake fluid out of the reservoir. Do not reinstall the reservoir until it is completely dry inside.

Once you have it installed again, pour the power steering fluid back in until it reaches the fill line, and you’re good to go.

Flushing the system

Unless you are pretty mechanically inclined and have the equipment necessary to flush your power steering system out, you will have to take the vehicle to a mechanic. You can drive it there, so long as it's close. The thing is, the brake fluid is already in there, and if the mechanic is close by, you can either drive it in or pay the extra cost to have it towed.

The average cost of having your entire power steering system flushed is $69.99, which includes topping the system off with fresh power steering fluid.

What fluid can you use in place of power steering fluid?

No matter what the circumstance, the power steering fluid is the best fluid of choice to use for your power steering system. However, if you are in a bind and have to use something else, some fluids will work just fine within your power steering system.

Transmission fluid

In most cars, you can use transmission fluid in place of power steering fluid. In fact, many vehicles literally use the same fluids for power steering and transmission. Even if they don’t, using transmission fluid is not going to damage your power steering system.

Transmission fluid is a good hydraulic fluid and will also provide the amount of lubrication needed in the power steering system.

Your engine oil

You can use it in a pinch, but you shouldn’t use it to the point where you are filling up the entire power steering tank with engine oil. It has a higher viscosity but retains some hydraulic fluid properties and is more than adequate for lubrication purposes.

Since it is a much higher viscosity than power steering fluid, engine oil should only be used in small amounts, just to get you through until you can get the problem fixed or top off the power steering fluid.

Standard hydraulic fluid

This is best used in emergency circumstances, but it won’t cause any kind of short or long-term harm to your power steering system. Hydraulic fluid also has decent lubrication qualities, but it's not good enough to be a long-term fix.

Final thoughts

Brake fluid never belongs in the power steering reservoir. If it ever gets in there, you should do everything in your power to get it out before cranking the vehicle up. The two fluids are completely incompatible with each other. Only use brake fluid for your brakes and use power steering fluid or one of the above-listed alternatives for your power steering system.