I came across this on a website last night, and I ordered these. Drop a tablet into a gallon of water, and you have a gallon of windshield washer fluid for about $0.08. Naturally, it will freeze if the temperature drops below 32°. I've read that adding eight ounces of isopropyl alcohol will keep it from freezing. I'll test that before I try it. Some sites recommend adding dish liquid to the mixture. I tried that many years ago, and it gummed-up the nozzles.

 

I wouldn't trust those. Because the best or top rated rated washer fluid out there isn't even expensive. Less mess, better made formula, long lasting name brand. $15.30 shipped for a gallon.

 

Not worthwhile making your own. In my case everybody around here sells windshield washer fluid, especially the RainX winter formula for about $5/gallon. It's rated for -45°C (- 49°F). There's a separate summer formula which contains detergent for the bug season.

It's not worth making your own because the cost is typically all in the alcohol (typically methanol) to give it that low freezing point. You have to be careful which alcohols you use because some may damage wiper rubbers or possibly the car paint. For a summer fluid you don't need alcohol, but you do need a good detergent for the bugs which won't clog the washer mechanism - or react with your paint.

 

$15 for a gallon of colored water is more than I'm willing to pay. Washer fluid used to cost well under $5.00. Now, it's closer to $10. Not for me!

 

The "cheap" fluid freezes, and I can't find it around here for $5.00.

 

I'll buy a giant bottle at Autozone for $5.00, thank you.

 

I prefer $0.08. No driving involved.