[alfa] Windshield washer antifreeze

[C M Smith <cmsmith@xxxxxxxxxxxxxxx>]

Standard winter windshield washer fluid is just methanol and water with 
blue dye. Sorry, I don't know the proportions but I suspect that even 
straight methanol would "freeze" in the thin film left after wiping. In 
Canada we routinely buy pre mixed stuff guaranteed not to freeze until 
minus 35 or 40 C ((minus 30 to 40 F)and I can assure you it doesn't freeze. 
It doesn't freeze hard even below those temperatures or our windshield 
washer systems would break. The effect you are noticing cannot be 
eliminated as far as I know. Thin enough films will "freeze" at cold 
temperatures. I recommend against trying to "formulate" your own for cost 
reasons, this commodity should be dirt cheap anywhere it is really needed 
just from market forces. But, you could experiment with 50/50 methanol and 
water and see how that works. if it works, try diluting with water until 
you no longer get the antifreeze properties you are looking for. I don't 
think the commercial mix is anything like 50/50. Alternatively, some 
chemistry buff, or book, might get you the freezing point you need for 
various concentrations of methanol in water.

The theory is that you should be able to clean the windshield at ambient 
temperatures which are likely to get your windshield dirty. Even road 
salted snow tends to stay on the road below around minus 10 C (14 F)so 
theoretically you shouldn't need to clean the windshield on very cold days, 
and my experience bears that out. Once the car interior is warmed up you 
can safely use the windshield washer down to around minus 15 (-13 F)and 
although the thin residual film will freeze it evaporates rapidly to leave 
a clear windshield. Below that I'm afraid the washer fluid will freeze to 
the glass and stay that way, usually. This stuff is not for de icing a 
windshield so if that's what you're looking for, they don't  make it for cars.

There is a commercial mix put out by Prestone, dyed yellow, which claims to 
be useable at lower temperatures. I have used it to assist in removing 
heavy ice from a  windshield with a hand scraper (standard equipment in 
Canada for winter driving) and can vouch for its antifreeze properties. It 
is roughly 3 times the cost of the blue stuff so I don't use it in the 
washer systems. We go through about 12 to 15 gallons of this stuff every 
winter in our four cars, sometimes more if the weather is warm (above minus 
10 C) and snowy. Regular on sale price for 4 liters (a little over a US 
gallon) is CAN$2.00 for the blue stuff.

I dilute the stuff modestly for summertime use, never more than half and 
half water and premix. As we are near the mountains we can get freezing 
weather just about anytime. I don't take the risk of freezing my washer 
system. For winter I use full strength with never a problem.

Cheers


Michael Smith
White 1991 164L
Original owner
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