Will warm water in winter crack your paint?

[adreed24]

I heard this story years ago and I want to know if there is any truth to it. Here it is:

In the cold, winter months, when the surface of your car is cold, you should not try to use warm, or hot, water and car soap, to wash your car.

The reason is, that the temperature difference between the cold paint and warmer water, will cause the paint to crack, and eventually come off in pieces, like a puzzle.

Anyone ever heard this before?

Any truth to this, or is it one of those car myths?

Thanks in advance!

[Murr1525]

Well, I dont think it is ever a good idea to use extremely hot water, winter or summer.

[rusty bumper]

I always use hot tap water to wash my cars with.......Well, I do add a little cold water to top it off, like maybe the last gallon or so.

Sure feels good in cold weather!

[explore_02xlt]

Originally posted by Rusty Bumper
I always use hot tap water to wash my cars with.......Well, I do add a little cold water to top it off, like maybe the last gallon or so.

Sure feels good in cold weather!

i've done that before, but my water only gets to like 130 so it's not REALLY hot. but i rinsed with regular hose water.

[Aurora40]

I use warm water in the winter to wash my cars. I try to pull them out of the garage to do this, so they are garage cold, not outside cold. But I've never had a problem. I try to sort of mist them a bit at first to make the temp change more gradual.

That said, I also worked at a local used-car place when I was unemployed (while obviously I was employed, but you get the idea). They used to pull cars in covered in snow and ice and hit them with very hot water from a pressure washer, wash them up, buff them out, and park them back on the lot. I never saw any windshields crack or anything like that. I wouldn't do that to my own car, but it seemed to work ok for them.

[Mike Phillips]

I've heard of this paint cracking topic before but never seen anything to substantiate. In Oregon during the cold months I always use warm water in my wash bucket to keep my hands from freezing while washing a car. Worked great for me.

[Jbirk]

You can use warm water with very little risk. It is all about the physics of temperature, pressure, expansion, and contraction.

Essentially, you want to heat everything evenly.

If it is -40 outside, water that is 130 is probably too hot, but if it is 110 outside, you can probably use 150 degree water and only you will get burned

That being said, heat evenly and don't do it to excess. If it is really cold outside and you do something stupid like pour a pot of boiling water on your car, you will probably have problems.


I really doubt warm water cleans much better unless you are trying to remove something like wax, so I recomend just using warm enough water to be comfortable. There is no need to freeze your hands, and there is no need to use hot water to wash your car.

If it is winter weather outside, you might try 80 to 90 degree water in the wash bucket.

*All temps in Farenheit

[Accumulator]

I suspect the "don't use warm water" thing is another urban myth.

Yeah, I'm more careful with my vehicles, and they're never really *cold* when I do them as the garage is climate controlled. But when I had the dealership we used to pull snow-covered cars in off the lot and treat them the way Aurora40 did. No problems.

Oh, and I do believe that warm water cleans better. Sure makes a difference in the washing machine, and what little I remember from high school science classes makes me think it's a good idea. Pressure washing goes a lot faster with hot water than it does with cold, even when I'm not dealing with things like grease.

[rusty bumper]

Originally posted by Accumulator
Pressure washing goes a lot faster with hot water than it does with cold, even when I'm not dealing with things like grease.

For years we had a car wash close by that used very warm water in their spray wands. I used to go down there often and blast off winter dirt, salt, etc. with no problems to speak of.

It's closed now, the guy lost his lease.

[Shiny Lil Detlr]

I do a warm-water QEW in the winter.... never seen any problems from it.

[Aurora40]

Originally posted by Accumulator
Oh, and I do believe that warm water cleans better. Sure makes a difference in the washing machine, and what little I remember from high school science classes makes me think it's a good idea. Pressure washing goes a lot faster with hot water than it does with cold, even when I'm not dealing with things like grease.

I do too. I find that a warm water hosing out of wheel wells is much more effective than with cold water. And in general it seems crud becomes unstuck from the paint more easily with warm hose and bucket water than with cold.

[Jbirk]

Any time you get the greasy grime up to a temperature closer to or beyond its melting point it removes much easier. Wheels can be sprayed with very hot water. Typically the break discs and drums can get wheels very hot... above the boiling point of water.

You can easily pull out a pressure washer and use 180 degree water without issue on wheels.