Easy Formula for DIY Windshield Washer Fluid

Are you tired of paying a lot for windshield washer fluid? Have you ever considered making it yourself? In this post we go through an easy formula to make your own windshield washer fluid. You can even adjust the proportions as necessary depending on whether you need a summer or winter fluid!

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Windshield Washer Fluid Ingredients

Windshield washer fluid is not complicated. It is simply a mixture of the following ingredients:

• Clean Water (for best results use distilled)
• Isopropyl Alcohol or Methanol
• Washer Fluid Concentrate or Dishwashing Liquid (1 oz)
• Blue Food Coloring (optional)

Warm Weather Formula

If you are operating in a warmer climate and will not see temperatures below freezing, then you do not need to worry about adding alcohol or methanol to your mixture. Add the other ingredients, but just use straight water.

Freezing Point of Water/Methanol Mixture (by Volume)

In order to avoid the washer fluid freezing in your vehicle, make sure that the freezing point of your mixture is below the lowest expected temperature your vehicle will encounter.

Below is a table showing the freezing point of pure water and methanol mixtures. Choose the appropriate % methanol using this table.

Methanol (% Volume)	Freezing Point (F)
0	32
10	20
20	0
30	-15
40	-40
50	-65

Freezing Point of Water/Isopropanol Mixture (by Volume)

Isopropyl alcohol – also known as isopropanol – is commonly known as rubbing alcohol. You can use this instead of methanol, it will just require a higher concentration to prevent freezing. The table below shows the proportions for pure isopropyl alcohol. If you are using 99, 91, or 70% isopropyl, then adjust the mixture accordingly.

Isopropanol (%)	Freezing Pt (F)
0	32
10	25
20	20
30	5
40	0
50	-5
60	-10
70	-20
80	-35
90	-70

Windshield Washer Fluid Recipe

1. In a clean 1-gallon jug, combine the water and methanol (if you do not have access to methanol, you can substitute rubbing alcohol), using the proportions listed in the table above.
2. For example, if your vehicle will be exposed to temperatures as low as -10 F, choose a mixture of 70% water and 30% methanol.
3. Add 1 oz of washer fluid concentrate or dishwashing fluid such as Dawn or Joy.
4. Add food coloring if desired. This step is optional and is mainly as a safety feature so that the fluid is not accidentally used for a different purpose.
5. Seal the jug and shake lightly to mix (avoid suds).

How to Add Windshield Washer Fluid

1. Pop the hood of your vehicle
2. Locate the washer fluid reservoir (look for a water fountain icon on the cap)
3. Open the cap
4. Pour in the washer fluid
5. Close the cap

For more details on specific vehicles, check out these posts:

• Toyota Corolla – How to Add Washer Fluid
• Toyota Sienna – How to Add Washer Fluid
• Honda Accord – How to Add Washer Fluid

Conclusion

I hope you found this recipe helpful!