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Poured Anti-freeze windshield washer to Brake Fluid reservoir

Idiot reporting here.
I had to travel to a cold area, and dropped by AutoZone to buy Rain-X all season window washer fluid (1 gallon) at 5 bucks.

I drained the washer fluid, and opened my Acura MDX bonnet. Then I searched for where to pour this brand new Rain-X orange color liquid in. Luckily I found cap, opened it, and started to pour. But after pouring about one cup of Rain-X, the reservoir filled up.

Strange - usually it used to take the full one gallon of the liquid. Suspcious of what I have done to my car, I asked the Auto-Zone employee, who kindly confirmed that reservoir is for brake fluid not for windshield washer. IDIOT!

I immediately drove my car to a nearby mechanic, who said it will take $120 to replace the brake fluid but they don’t have time until 8 days later. I called another mechanic who said who have never done that before, and cannot tell how much it is going to cost unless they open it up.

I called my friend mechanic, far from where I travel, and he told me to use Turkey baster to suck the brake liquid reservoir as much as possible, and then fill it up with newly bought brake fluid.

So did I. But before I could do that, I had to drive local town about 30 plus minutes to buy parts and brake liquid. During that time, I did not feel any strange things when I used brakes.

So here come my question.

  1. Did I earn some time before I can drive my car back to my home town (250 miles) and visit my friend mechanic?
  2. Or I should stop driving my car immediately and let my car towed to the mechanic? And stay here until the local mechanics have time to fix my car?
  3. Is the freezing temperature going to make my braking system work worse?

Please advise me with you best info… I admit many of my behaviors were idiotic.

Forgot to mention. I sucked out about 9 oz of the fluid from the brake fluid reservoir using the turkey baster, and I poured a new brake fluid (dot 3) about 11.5 oz to the top of the reservoir.

Once you stepped on the brake pedal, the washer fluid started mixing with brake fluid.

Don’t drive the vehicle until the entire brake system can be flushed.



Your brake system will operate normal with 50% water until the brakes become very hot, like when descending mountain grades. Since you have removed most of the washer fluid there is very little water or alcohol in the brake system. The problem with water in the brake system is corrosion after a period of time.

Drive to your mechanic and have the brake system flushed.


My question is why was the brake fluid resevoir down a full cup of fluid anyway? That’s a pretty serious amount to be lacking.

I suspect the brake fluid is fully contaminated considering all of the driving that has been done before the turkey baster was used and it needs to be flushed out quickly. I would suggest calling everyone in that area with a Google search. A fluid flush should not be that time consuming. Surely someone can work your vehicle in. If you end up having to drive it home then go easy on the braking.

Aged or contaminated brake fluid has a lower boiling point and is the cause of brakes locking on Harley motorcycles and the issue of boiling brake fluid (other than DOT 5) has been around for decades. Two year fluid change is recommended. It’s never happened to me but it did happen to a riding buddy of mine when his HD dresser rear brakes locked up at 70 MPH. Luckily he skidded out of that one with no physical injuries.
Last I read NHTSA had 400,000 investigations on this issue with Harleys alone in just a few years time span but the issue goes way back further than that.

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It’s been done.

Thank you for educative replies. I take this blunder and mishap as an opportunity to learn.

One confusion of mine is it appears that some pieces of information I heard from various sources are not compatible. Are these all true?

  • Brake fluid do not circulate.
  • Braking actions should have already mixed up brake fluid and windshield washer fluid
  • Brake fluid is ligher than windshiled washer fluid
  • Windshield washer fluid would stay in the reservoir for some long period of time and it would take long time to get mixed up with brake fluid

Brake fluid doesn’t circulate like coolant. However it does move back and forth a bit each time you brake, resulting in a slight mixing action each time. If you had used the turkey baster before ever applying the brakes, you would probably have been okay here.


I’m certainly glad that you did not go to the mechanic who said he had never done it before! If he hasn’t bled a brake system, what has he done?
All these stories here about lousy mechanics surely makes me appreciate the guys I use.

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I know of 2 people who are from OK and on trips to CO experienced brake issues in their Altima due to locking up. One is a couple who have a cabin in northern CO and when getting it checked they were told the brake fluid had not been changed and was trying to boil. A fluid flush fixed that problem. How were we to know they asked. Read the owners manual they were told…
They asked me when they returned and I just reiterated they were told correctly.

Another couple experienced badly fading brakes in a Jeep Cherokee while coming down Pike’s Peak. Same cause; same cure; same how were we to know question with the same answer.

Thank you all for your advice and education.

I just safely finished 250 miles drive with 7000 feet descent. I used engine braking only throughout this trip with a very limited depressing of brake pedal in local traiffic stops. During the trip I did not feel a spongy brake syndrome. Just in case, I carried an extra can of brake fluid, which I ended up not using it. The next busines I am going to tender immediately is to bring my car to the local mechanic to bleed the brake fluid.

I learned a couple of things this time, and I like to share with you.

  • Folks who kindly answer in this forum is not merely sharing their knowledge. In fact, you are guardians of transportation safety. Your answers help drivers, passengers, other fellow drivers on road to stay safe. Big kudos.
  • Engine braking is awesome. Using engine brake almost only in the highway made me keep more sufficient safety distance, drive more proactively by watching others, drive more defensively. Also the ride was smoother than the one when I solely used pedal braking.
  • As a datapoint of mine, assuming my windshield washer fluid and the brake fluid got mixed up to an unidentified degred, a light use of pedal brake in local roads (30 min) in a cold climate zone does not lead to a vapor lock.

Thank you

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