No, you shouldn’t use brake fluid in the power steering system. The two fluids have different chemical compositions, and mixing them can damage seals, cause steering loss, and lead to costly repairs. If you’ve already added brake fluid, drain and replace it with the proper power steering fluid.
Watch this video tutorial: A visual guide that explains the topic in detail.
What the fluids actually are
Brake fluid is a glycol‑based or silicone‑based hydraulic fluid designed to withstand high temperatures and prevent boiling under hard braking. Power steering fluid is usually a mineral‑oil base or synthetic hydraulic fluid formulated to keep the steering pump and rack lubricated while providing smooth pressure.
Why they’re not interchangeable
The key differences are viscosity, lubricity, and seal compatibility. Brake fluid is much thinner and more aggressive toward rubber and polymer seals used in power steering assemblies. Using it can cause seals to shrink, leak, or fail outright, which translates to a loose or unresponsive steering wheel.
How to tell if you’ve used the wrong fluid
Symptoms appear quickly:
- Steering feels gritty or jerky
- Whining noise from the steering pump
- Visible fluid leaks around the pump or rack
- Power‑steering warning light on the dash
If any of these show up after you topped off the reservoir, assume the wrong fluid was added.
Fixing the mistake
- Disconnect the battery for safety.
- Place a drain pan under the power‑steering pump and remove the reservoir cap.
- Pull the return hose to let all fluid flow out, then flush the system with the correct power‑steering fluid until it runs clear.
- Refill to the manufacturer‑specified level and bleed any air by turning the wheel from lock‑to‑lock several times.
- Start the engine, check for leaks, and verify smooth steering before driving.
Doing this yourself usually costs under $50 in fluids and a few gallons of waste oil. If seals are already damaged, expect a $150‑$300 repair.
Preventing a repeat mistake
Always read the label on the fluid container. Most modern cars label the power‑steering reservoir with the exact fluid type—often “Dexron‑II” or “ATF‑type.” Keep a small notebook in the glove box with the recommended fluid for each system; it’s a habit that saves time and money.
Additional Resources
Here are some additional resources that provide more detailed information about this topic:
- Read more on Car and Driver
- Read more on Motor Trend
- Official information from NHTSA (National Highway Traffic Safety Administration)
- Official information from SAE International
Frequently Asked Questions
Can I mix a little brake fluid with power steering fluid temporarily?
No. Even a small amount can degrade seals and compromise steering performance.
What if my car uses hydraulic power steering?
Hydraulic systems still require the specific power‑steering fluid listed in the owner’s manual. Brake fluid will still cause seal damage.
Is there ever a situation where brake fluid is acceptable in a steering system?
Only on a few rare, older European models that were designed to use DOT‑3 brake fluid for steering, but those are the exception, not the rule.
How often should I change power steering fluid?
Most manufacturers recommend every 50,000–75,000 miles, or every 4–5 years, whichever comes first.
Will using the wrong fluid void my warranty?
Yes. Most warranties state that using non‑specified fluids is a breach of the service agreement.