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2016 Accord - I just poured windshield fluid into the brake fluid container

I was already having one of the worst weeks of my life so please go easy on me… I am well aware how stupid this mistake is.

As the title said, I poured antifreeze into the wrong container. I realized my mistake pretty quickly and pushed as much out as I could but some clearly mixed in. I had little choice but to drive 15 miles home and this has to wait for tomorrow. I’ll be taking it into the shop first thing in the morning. I’m finding conflicting information on Google… Is this just a situation where they flush the fluid or am I looking at serious repair costs?

You would be surprised how often things like this pop up on this board. I doubt there will be any serious damage. The flush is a good idea, was that the mechanic suggestion? The major question is why was brake fluid low.

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This happened about 2 hours ago so I haven’t had a chance to talk to a mechanic. Looking online a few people said it would be as simple as a flush but others said it would be a bit more involved. I also want to make sure the mechanic doesn’t try to fleece me by over playing the damage.

The brake fluid wasn’t low. My first hint that I picked the wrong container was how quickly it topped off. I was doing this in the dark in a hurry in -13 windchill without gloves. My window was so obstructed it was unsafe to drive without cleaning the windshield so I had to stop at a gas station and refill.

I suspect you’ll be ok with just a flush/replacement of the brake fluid. Probably time anyway. Others may disagree. There was another thread on this not too long ago if you want to look for it.


Alright, I think I’m freaking out about this more than it deserves. I’ll update for posterity when I get the actual costs.

Thanks for the advice.


No, there is plenty to be concerned about. Water in the brake lines can be very dangerous. But a full flush would remove the water and things should be okay after that.

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Can you suck all the water and brake fluid out of the reservoir before the water gets out of the reservoir? Suspecthathe water is heavier than the brake fluid and will sink to the bottom and go further. (Can water diffuse into the brake fluid?)
Just flush the system. Maybe good to flush the brake system, anyway.

The water seemed to be sitting on top not mixing. I don’t have a turkey baster or anything to suck it out. I have an appointment at the shop in an hour so this is getting looked at ASAP.


How low was the brake reservoir? I can’t believe that you’d be able to put in more then a couple ounces.

Was it antifreeze or windshield fluid? HUGE DIFFERENCE.

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Before driving, I’d absorb it out with paper towels until all the water and some of the brake fluid was gone. But does brake fluid absorb water? If so, just flush the system.

I didn’t get more than a few oz in. I pushed as much as I could out and tried absorbing more. I’ll give it another go with paper towels before leaving. It was windshield fluid.

Brake fluid is hygroscopic, and it absorbs moisture just by aging, hence the importance of doing a brake fluid flush every 3 years, even if one didn’t pour the wrong fluid into the master cylinder.

You do realize that as the brake pads wear, the fluid in the reservoir drops?


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Folks, the OP stated the brake fluid was NOT low, he was not trying to add brake fluid.

The windshield washer fluid resevoir is what he intended to add washer fluid to but working hurridly in the dark, at a gas station, in severe winter conditions he mistakenly added washer fluid to the wrong reservoir receptacle.


Just got it back. All they had to do was a brake flush. All said and done it was $225. I assume it would have been cheaper if I went to not the dealership in not downtown Chicago but such is life. Either way my worries were closer to this, so I count it as a win


It depends on the dealer. Ours is fairly competitive with independent shops, but that can vary dealer to dealer. Glad you are ready to roll!

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It appears the OP had more to be concerned about than washer fluid in the brake container. Glad you made it out alive.


With the windshield fluid sitting on top of the brake fluid, it might have helped to just add more brake fluid so that the water overflowed. The baster and the towel were also good suggestions, especially if done soon. I realize the OP had cold weather that would have made any personal work much more difficult. Plus, I still would have recommended a flush, but I would have done it by disconnecting a brake line near the caliper, rather than running water into the caliper.