Same here. Starting to think that “hot water cracks windshields” may be something of a UL. Maybe it was true in the 1950s but some kind of more advanced safety glass has eliminated the risk. Or else the conditions to bring about cracking have to be very specific.
I cracked my windshield pouring lukewarm water on it last winter., and temps were only in the 20s, so it’s no UL, though it may very well have been a windshield of inferior quality (I bought the car used).
Interesting thread on the Mythbusters forum about using hot tap water to clear ice off of windshields.
The responses are mixed, but there are many anecdotes of people using hot water safely for de-icing. There are also some opposing anecdotes. I wonder if it’s a technique thing – do it one specific way, and it’s fine … but do it in a trivially different way, and you’ll crack the windshield for sure. Maybe year, make, and model of car matters, too – perhaps not all windshield installations allow for the necessary “give”. Or something.
Well, (a) I don’t think the pH of a 50/50 vinegar/water mixture is going to rapidly dissolve my car, and (b) if you’d seen my car, you would realize that if it did, this would be the least of its problems.
Hot water poured slowly from the top and let trickle down slowly (relatively) compared to throwing a whole bucket of hot water over the whole windshield in one go might be the deciding factor + how tight the windshield is installed and how much room in that installation there is for dimensional change of the glass.
*:: ask me why I think this? ::: I don’t mind looking like an idiot. *
Oh, and with boiling water on a windshield with only a thin layer of ice at -10 F I bet I can destroy any stock auto windshield. There is hot and then there is hot.
You won’t look like an idiot. Clearly, plenty of people use hot tap water for this purpose with no ill effect.
Fact is it will pit both the paint and the windshield itself. But hey, like you said, it’s your car.
For those Dopers who can avail themselves, I’d like to recommend one of the greatest inventions since the ballpoint pen: the remote starter. For the occasional environmental “cost” of running the car for ten minutes or so, we have the chance to go out to the car, quickly and effortlessly scrape the ice off all the windows, and sit down in a moderately warm car, with no impeded vision. When we’re having -10 and -20 nights, such a cost is more than worth it. I had an aftermarket kit put on my wife’s '01 Civic, and I’ve never spent money better.
Your climate must be more kindly than ours. If it’s cold enough, just the moisture from your breath is enough to cover the inside of the windshield with frost. Much safer to let the defroster get up to operating temperature before driving.
But don’t put the defroster on high, right at first - I’ve cracked windshields from the inside doing that on subzero days.
Which reminds me of the quip (that married men know too well) that free sex costs a lot more than the sex you pay for.
This is not likely. True, if you soaked your car in vinegar for a long time you would have problems, but acetic acid is volitile so it won’t stick around. For the breif time that the acid will be in contact with your car, there will not likely be any problem.
Salt is much worse for your car and people drive in that all the time.
Thanks for the input.
Now that you mention it, I seem to remember doing this after a sleet storm. Maybe the ice has to be a certain thickness.
It’s funny - stores sell a deicing chemical in a spray can, made just for this purpose, and it works WONDERFULLY!!! :D:cool::p:) It’s widely available, not expensive, and I would no sooner be without it than I would be without a scraper.
Yet I am apparently the only person on the internet who uses it. 
Ya know, I’m going to try some. I’m having shoulder surgery in 4 days and scraping the windows is going to be a real pain. That could really really help.
I came in here to mention just that. In really cold climates, like IL where I grew up, you’ll freeze your ass off trying to scrape a thick layer off.
I wonder what its active ingredient is. Some of it is aerosol; I think Rain-X has one that’s just a pump. Rubbing alcohol maybe?
BTW Rain-X also makes washer fluid with de-icer in it. Not that you’d use it to clear your windshield first thing in the morning, but if driving in freezing rain or something it could be advantageous.
Mine (Prestone brand) says it contains methyl alcohol and ethylene gylcol.
Thanks for the info…I suspect you could make your own and save some money.
The methyl alcohol is prolly quite flammable…not the same as isopropyl, i.e. rubbing alcohol. Ethylene glycol is the main (?) ingredient in antifreeze. But of course they probably dilute the mixture, maybe to avoid harming the paint and/or to keep your car from going up in flames if you’re smoking when applying it.
I’ve tried a mixture of two parts rubbing alcohol to one part water and it works well but not as good as the Prestone de-icer, especially below -20, YMMV.