Brake fluid



My wife added power steering fluid to the brake fluid, how worried should I be?


Remove as much of the PS fluid as possible from the reservoir (a turkey baster will work, but throw it away when you’re done), then refill with brake fluid.

If you think the PS fluid has gotten into the brake system, you can have the system flushed and refilled with clean fluid. Depending on the age/mileage of your vehicle this service may be due anyway.


Well, they are both hydraulic fluids, so one would think that it would be ok however; I accidentally did this once myself. I discovered the error as I was pouring it in the reservoir because the fluids did not mix at all. I have a home-brew vacuum pump that I used to suck the reservoir dry and then refilled with brake fluid.

Aside from different densities the power steering fluid also has a higher viscosity, so that is probably not a good thing.

If you have already cycled the brakes you will have to bleed the entire system, unless you can visibly see that all the PS fluid is still floating on top.


A hydraulic system can operate on virtually any liquid. Brake fluid is chosen for its low freezing point and high boiling point. When altered with a contaminant, these properties will be altered.

Follow the instructions of the guys above. Remove whatever you can and refill with the correct fluid. Then don’t worry about it. Some day you will go for a brake flush as part of normal maintenance.


In some cases it can cause a problem like destroy the pump…Or just not work properly. Remove what you can from the resevoir and you’ll be fine.

Years ago brake fluid and PS fluid were the same.


Thank you.


Since most people believe brakes are rather important, I would suggest being diligent about this one.

I would make sure I did a brake fluid flush after trying to get it cleaned up via Lofer"s suggestions.

Brake fluid should be change every two to three years anyway. It will absorb water and that can cause big problems when you least want them.


I’ve heard of cases where petroleum-based oils in a brake system did damage to the seals. I can’t substantiate those because I didn’t see them, but I’d feel better flushing the fluid.