What to Do If Windshield Washer Fluid is Added to Brake Fluid?
3 Answers
If windshield washer fluid is added to brake fluid, it must not be used any further. It is essential to visit a professional repair shop to replace the brake fluid with new one. Adding windshield washer fluid to brake fluid, even if no chemical reaction occurs, will dilute the brake fluid, lowering its boiling point. There is also the possibility of a chemical reaction causing the brake fluid to deteriorate completely. There are various types of fluids used in cars, such as engine oil, automatic transmission fluid, manual transmission fluid, brake fluid, coolant, power steering fluid, and windshield washer fluid. Each of these fluids has different functions and purposes, and they must never be mixed. If any fluid is mistakenly mixed with another, it must be sent for repair immediately to avoid potential safety hazards due to delay.
I've experienced this a few times, so handle it carefully. Once you add windshield washer fluid to the brake fluid reservoir, mixing them can cause problems because washer fluid usually contains water or additives that contaminate the brake fluid, lowering its boiling point and leading to vapor lock or complete brake failure when braking—you might not be able to stop the car. My advice is to pull over immediately and absolutely do not start the engine again—it's too risky. Call a professional towing service to have your car towed to a reliable repair shop. They’ll help you flush the entire brake system, including draining the contaminated fluid, cleaning the lines, and refilling with fresh brake fluid. The cost ranges from about $200 to $1,000, depending on the car model and extent of the damage. Afterward, don’t forget to test the brake responsiveness to ensure safety. In the future, double-check the cap labels before refilling—the brake fluid reservoir is usually black, while the washer fluid is in a separate location. A sticky note can help avoid confusion.
Oh, this situation is quite common. After hearing about it, I suggested taking quick action. Adding substances like alcohol or water to the brake fluid can cause it to absorb moisture and foam up, which is dangerous as it may lead to brake failure. Quickly turn off the engine, park the car, and call for a tow truck to take it to a repair shop—don't try to fix it yourself. The mechanic will use professional tools to flush the system and may need to replace the old fluid and some components. The whole process could cost a few hundred dollars. I recommend using this as a lesson to label each fluid reservoir with colored tape to avoid mixing them up next time. Safety comes first—don't skimp on this expense.
