homemade windshield washer fluid ... Isopropyl alcohol vs methanol

Joined
Jun 12, 2005
Messages
6,568
Location
North Texas
Going to start making my own windshield washer fluid. Which is better to use as a deicer? Don’t laugh at me. Yes I live in north Texas. We do get below freezing at times, lol. Most concentrated washer fluids say to use methanol. Thanks.
 
Last edited by a moderator:
It isn't about being cheap. The gallon stuff you get at the store doesn't really "protect to -20* like it says on the bottle, and pills sometimes have a tendency to come out of suspension and clog the motor/lines. Get the gallon jug for convenience, and pour some 91% Iso alcohol in it. Whn you know its going to be one of those "Icer's", make sure you purge the lines until the ISO makes its way out onto the window. Otherwise, your lines freeze up while your reservoir stays unfrozen.
 
I use the individually sealed tablets. Works out to be .10 a gallon. In the winter I add 1/2 cup of 99.9% Isopropyl alcohol to the gallon of washer fluid. I'm good on washer fluid for the next 10 years :ROFLMAO:

Windshield washer tablets - https://www.amazon.com/awave-bloom-Windshield-Gallons-Window-Glass/dp/B0B9S1FR6Z/

4 Gallons of 99.9 Isopropyl alcohol - https://www.amazon.com/MaxTite-Isopropyl-Alcohol-99-9-Gallon/dp/B08G57WSV2/
Thank you. I saw some blue concentrate. I may use distilled water with it.
 
It isn't about being cheap. The gallon stuff you get at the store doesn't really "protect to -20* like it says on the bottle, and pills sometimes have a tendency to come out of suspension and clog the motor/lines. Get the gallon jug for convenience, and pour some 91% Iso alcohol in it. Whn you know its going to be one of those "Icer's", make sure you purge the lines until the ISO makes its way out onto the window. Otherwise, your lines freeze up while your reservoir stays unfrozen.
Had that happen to me on a company vehicle I used for the weekend. They had used water mostly. I filled the reservoir with a gallon of -20F. I never used the fluid on trip up and it was about 0F that night. Lines were frozen solid, I had to sit with engine running in an area away from wind for 30-45 minutes before it finally thawed.

@ARB1977 - read the directions on the concentrate bottles. The ones I had in the past were like 1:1 for 0 degree which on a 16 ounce concentrate doesn't go very far.
 
If you don't mix it right, to the point that it may damage your hoses, wouldn't it dissolve the wipers themselves?.,,
You can buy WW fluid that's rated for -49C so that's about 57% methanol (by volume). To be safe just keep your mix at 30-50% methanol.

But like has already been mentioned it's very difficult to beat the sale price on the shelf. Just bought a years supply for $3/gal (Canadian) and that was brand name -40C, not the cheap, blue, no-name stuff at -30C.
 
I wouldn't mess with it. I am also in North Texas. I made my own for years. Never had trouble with freezing, but somehow it ultimately clogged the hoses and nozzles. Took me a good amount of time and effort to clear them. I used denatured alcohol, a tiny bit of dishwashing liquid, and R/O water. Just not worth it.
 
If you are mixing your own windshield washer fluid, I don't recommend using methanol.
Methanol is corrosive. "Methanol can cause corrosion in metals such as aluminum, magnesium, and carbon steel. It attacks the protective oxide layers on aluminum, leading to significant corrosion over time. Under specific conditions, such as when mixed with water, methanol can exacerbate stress corrosion cracking in carbon steel, especially if the steel is under tensile stress."
"Methanol acts as a solvent for many rubber compounds, leading to swelling and potential brittleness over time. Prolonged exposure can cause rubber to lose its strength and elasticity, making it less effective in applications such as hoses, seals and gaskets."
"Methanol's impact on plastics is generally less severe than on rubber, but it can still cause issues. Some plastics may resist methanol better than others; however, there are concerns that methanol can attack certain types of plastic components, particularly those used in automotive applications like washer nozzles. While immediate damage may not occur, long-term exposure could lead to degradation or failure of plastic components over time."
Ethanol and Isopropyl alcohol are better choices. That being said, most commercial winter (or all weather) windshield washer fluids contain methanol. Why? It is WAY cheaper.
 
If you want to lower the freezing point of water to 0°F, this is what you have to add:
23% methanol
33% ethanol
45% propanol

If you want to lower it to -20°F, this is what you have to add:
33% methanol
40% ethanol
60% propanol

You may do your math from here.
 
Going to start making my own windshield washer fluid. Which is better to use as a deicer? Don’t laugh at me. Yes I live in north Texas. We do get below freezing at times, lol. Most concentrated washer fluids say to use methanol. Thanks.
why poisonous methanol when ethanol exists, which is also less corrosive?
 
If you are mixing your own windshield washer fluid, I don't recommend using methanol.
Methanol is corrosive. "Methanol can cause corrosion in metals such as aluminum, magnesium, and carbon steel. It attacks the protective oxide layers on aluminum, leading to significant corrosion over time. Under specific conditions, such as when mixed with water, methanol can exacerbate stress corrosion cracking in carbon steel, especially if the steel is under tensile stress."
"Methanol acts as a solvent for many rubber compounds, leading to swelling and potential brittleness over time. Prolonged exposure can cause rubber to lose its strength and elasticity, making it less effective in applications such as hoses, seals and gaskets."
"Methanol's impact on plastics is generally less severe than on rubber, but it can still cause issues. Some plastics may resist methanol better than others; however, there are concerns that methanol can attack certain types of plastic components, particularly those used in automotive applications like washer nozzles. While immediate damage may not occur, long-term exposure could lead to degradation or failure of plastic components over time."
Ethanol and Isopropyl alcohol are better choices. That being said, most commercial winter (or all weather) windshield washer fluids contain methanol. Why? It is WAY cheaper.
Thanks I went ahead and ordered 99.9% isopropyl alcohol and blue windshield washer liquid. I plan on using a gallon of distilled water also,
 
Back
Top Bottom