If I have access to a stove, a pot, running water, and rice, I’m probably at home and can just replace the hose. 
Urine has salts in it, and that lowers the freezing point a bit, but not too significantly. It will freeze at somewhere in the neighborhood of 28 degrees F. This will vary based on composition (how much water do you drink? How much alcohol do you drink? How efficient are your kidneys?) and age (of the urine, not the person).
It sounds like you have never bought a $200 work car or winter beater 
Well if it’s just a bad hose leaking put some Duct tape on it @shadowfax and don’t tighten the radiator cap. EVERYBODY knows that.
You are very correct! Never have, never would.
CSA
It’s mostly water so it would be 32 F.
No disrespect meant but you sound like you come from a well to do family but other’s including me did not and had to do what ever it took to get by think appaliachia.
You’d be amazed what we did in Nam to keep some of our Jeeps running. I was in at the end of conflict and parts were short supply by then, yet we still needed the jeeps and other trucks. Many butcher jobs just to keep the vehicles road-worthy (barely).
During the Iraq war soldiers were improvising to make their Hummer’s more bomb proof.
You can replace all the radiator hoses for under 100 bucks. You can often replace the one that’s leaking for less than 20. You cannot replace a head gasket or a warped head for that price.
Yes, if you’re deeply impoverished and can’t spare the cash for a $20 radiator hose from Walmart, a home remedy might get you to your next paycheck, if you’re lucky. But if you then spend that paycheck on stuff that has become more important because, hey, the car’s working right now, then you are likely to run into problems down the road.
The “fix it right” idea isn’t meant, at least from my part, to impugn people who don’t have money - it’s meant to say that if you DO have the money to do it right, for cripes sake do it right instead of trying homeopathic car repair just to save a buck.
I grew up in the hills of NYs Southern tier in an area today classified by the feds as part of Appalachia, Where I grew up never recovered from the depression. The word creek is pronounced “crick”, a small stream coming down between two hills is a “run” and a very snall valley is a “hollow” or if you are backwoods enough a “holler”.
I grew up so poor that when I got married, I had to borrow the money for a license.
My first car was $20 and if it broke I had to get parts from a junkyard and fix it myself.
I am no longer broke and buy new cars for cash now, but I still sympathize with those that still have to make
do.
Because of trucking deregulation I was frequently out of work as companies closed. I added up the number of trucking companies I had worked for and got to 40.
The only reason I have some money now is due to learning how to live on very little and not spending everything you make when you are flush.
Our favorite vacations are still a cabin in the wooded hills with hiking trails and wildlife around. All the books I read come from the public library which saves me from having to buy a lot of bookshelves.
I hate changing cars and keep them as long as I can.
The only breakdown with my car that stranded me was a timing belt that broke at only 4 years and 43000 miles.
Luckily it was on a bus route that went within 3 blocks of my house and had a parts store on it. I got the belt and tools and fixed it at the curb where it stopped.
Sure I used tin cans and hose clamps to fix a tailpipe broken, and sure I replaced a gas pump in my 72 f100 at 18 degrees while moving from ND to southern IL in january while towing my nova, girlfriend, her son, my pony tail palm, and I was so glad we limped into the napa parking lot half an hour before closing on a saturday got the pump and changed it in the parking lot. I still consider that a lucky day. Boy that gas on your hands gets cold, sure more stories available, enough for today.
This may be off topic somewhat but since we are talking about home-made repairs I have one – Returning home from Key West on a Sunday my generator (yeah, way back then) froze up and threw my fan belt. Well the car had only one fan belt to run the generator and the water pump. I cut the fan belt to make one piece, Measured it to go around the pully and the water pump, cut it to that size, and punched a hole in each end with my pocket knife. Then I took a short piece of wire from a coat hanger and wired the two fan belt ends together. That would work for about 5 miles and the fan belt would come off. I kept stopping and putting it back on until I came to a gas station. I handed the connected fan belt to the attendant and told him I needed a new one that size. He had one that was the perfect size and I put it on. It got me home and 2 weeks later I traded the car with the generator still frozen and the new fan belt still on.