How to keep windshield wiper fluid from freezing.

Dear Car Talk

Dear Car Talk | Feb 01, 1993

Dear Tom and Ray:

This may seem trivial, but it really frosts my gizzard: My windshield washers don't work in sub-freezing weather. In October, I switch from water to "guaranteed to 25?? below" washer fluid, so that by the time we have hard freezes, I have gone through two full tanks of this blue stuff (why is it always blue, anyway?). BUT, then a good freeze comes--say, a couple of days in the low twenties--and the washer won't work again until a thaw. At first I thought some precipitation had frozen just in the nozzle, but when I disconnected the hose from the nozzle, nothing comes out of the hose either. Is water getting in the system from some other path? Is the washer fluid I buy a rip off? Does the water I use in the summer somehow hide out, and then jump back into the hose when it gets cold? Why am I too cheap to take it to a dealer? Thanks for any insight.

TOM: Well, of all the questions you asked, David, the only one we feel confident in answering is "why is the stuff blue." But we'll get to that in a minute.

RAY: The reason the stuff is freezing is because the washer fluid you're buying IS cheap junk. The fact that it was $1.99 for a case of six should have been a dead giveaway, Dave.

TOM: It doesn't freeze in the reservoir bottle til 25?? below, because there's too much of it there (for the same reason a lake doesn't freeze as quickly as a puddle on your driveway). But when a thin stream of this washer fluid sits overnight in the rubber tube that feeds the washer, it freezes and plugs it up.

TOM: Try this experiment. Put a very thin layer of this stuff in the bottom of an ice cube tray and put it in your freezer. Come back 12 hours later, and I bet you'll find thin, little ice cubes.

RAY: And that's why the stuff is blue, by the way. To warn the guests at your next cocktail party that it's NOT water, in case you forget.

TOM: The best washer antifreeze you can get is the concentrated stuff they sell at auto parts stores. Buy a bottle of that and try it at a stronger concentration than even they recommend--that is, add less water than they suggest--just to test the theory. If it doesn't freeze, then you can try lower concentrations. Better washer fluid will solve the problem, Dave, because there's really no other way for water to get in there.

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