Don't wash your car at home?

I got this little tidbit in email from my mortgage guy (along with a lot of other tips, mostly financial, that he likes to send out every month). This is the first time I've ever heard someone say that washing your own car can be dangerous. Any truth to it?

Believe it or not, an automatic car wash is not only more convenient, but it can also be much safer for your car than washing the car at home. Why? If your car is washed by hand in direct sunlight, the drops of water turn into mini magnifying glasses, which can cause the sun's rays to burn spots into the paint - and this could cost you big when going to resell the vehicle. Additionally, many use harsh household soap products which remove protective wax and leave a chalky residue on the surface. Taking this into consideration makes the $10 to $15 automatic car wash fee look pretty reasonable.

I use a high-pressure washer with 'proper' carwash detergent on the driveway. If I avoid the hottest part of the day, is that safe?

-Tim

[Cervus]

If your car is washed by hand in direct sunlight, the drops of water turn into mini magnifying glasses, which can cause the sun's rays to burn spots into the paint - and this could cost you big when going to resell the vehicle.

In a word, no. Otherwise we'd see visible effects every time the sun came out after a rainstorm. Also, automatic car washes don't dry your car either. Your drive it out wet and all those little water droplets are exposed to direct sunlight as you're driving.

[Lainie]

It may , however, be more environmentally sound to wash your car at a commercial do-it-yourself car wash than at home, depending on how the car wash handles its runoff.

the drops of water turn into mini magnifying glasses, which can cause the sun's rays to burn spots into the paint...

So when I get out of the pool, the sun is burning holes in my skin?????

[DawnStorm]

Well let's all stay inside, lest we work up a sweat and burn to death.

[DrRocket]

I wash my car at home most of the time. I do wait until my driveway is in the shade before I do it. More a matter of comfort than anything else. (I'm not a sun worshiper.) I find that if I let the water dry before I can towel it off, it will leave spots, but they can be removed by re-rinsing the car. More a matter of inconvenience and extra water than damage. I find that claim to be highly exaggerated.

Perhaps the mortgage guy owns a stake in the local chain of car washes.

I DO use wash soaps designed for cars, as dish detergents will damage any coat of wax that may be on your car. My brand of choice is Maguires.

Also, per state law here, car washes are equipped with grease traps to catch and hold any such material when you clean your engine compartments.

[Aud 1]

This is silly. Think about it. Every time it rains and the suns comes out there would be damage. If the driver has a garage and always parks in a garage while out there might be a long term difference but I doubt it.

The most dangerous part of washing your car at home is slipping on the soapy wet driveway. (Or possibly being seen in a wet t-shirt by your neighbors.)

[Gayle]

I know you shouldn't water your plants on the leaves during the day because the sun will burn the leaves and petals. Not to mention it's inefficient and wastes water.

I wish my groundskeeper knew this. The roses look like crap this summer.

[Delta-V]

Originally Posted by Cervus

In a word, no. Otherwise we'd see visible effects every time the sun came out after a rainstorm. Also, automatic car washes don't dry your car either. Your drive it out wet and all those little water droplets are exposed to direct sunlight as you're driving.

Some automatic washes do dry - They've got giant hair-dryer things, but they don't always get all the water off. But, yes, you do get the same effect in a rainstorm. And since you don't usually dry the car immediately after the rain, I don't see hand washing being any worse in this respect unless you never leave the car out in the rain. Water spoting is generally caused by letting the water spots dry out, leaving behind whatever dust is contained in it. Not sure how much a problem the magnifying effect would be since the focal point surely isn't right on the surface.

It seems to me that the 'brushless' ones just don't get the car very clean. Then if you use the 'WAX' option, they trap the dirty parts under the wax and it's even harder to clean' The 'brush' ones leave fine scratches.

They're assuming, of course, that the automatic car wash itself doesn't use harsh chemicals. Hand washing with the wrong detergent will, as they say, remove the wax. Not sure about what the 'chalky residue' is supposed to be, unless you use Comet or Bon Ami on you car . Dawn dishwashing detergent will definitely remove wax (in fact, I use it to remove the remaining wax if I'm going to wax after washing). Otherwise, use a good detergent specifically designed for car washing. Like anything else, there's good hand washing techniques and bad hand washing techniques and good and bad towels/mitts/etc.

[Gayle]

Originally Posted by Delta-V

And since you don't usually dry the car immediately after the rain, I don't see hand washing being any worse in this respect unless you never leave the car out in the rain.

But the sun isn't usually shining after it rains.

Thanks for the replies. I thought it sounded silly...

As for the "sun after it rains", at least here, it's pretty rare to get rain followed by intense sun. By the time the sun tuned intense, things would be pretty dry. On the other hand, I could see someone washing their car at 1PM on a 100+ degree day where the sun is much more intense...

And as Delta noted, most automatic car washes I've been through DO dry the car -- either via gianormous blowers/fans, or with soft cloths that drape over the car as you drive through. The car may be damp upon exiting, but never as wet as it would be when washing it.

-Tim

[Katness]

Oh goodie!! I'm not just being a princess by using the automatic carwash almost exclusively!! I'm helping the environment as well as protecting my investment in my car!

Actually, I drive an SUV and reaching the roof when hand washing it is darn near impossible!

[Cervus]

Originally Posted by Gayle

But the sun isn't usually shining after it rains.

Down here it's not uncommon for it to rain while the sun is shining.

And the sun usually comes out shortly after a rain, at least here. I think the situation in the OP would be much more of a problem in Florida, where the sun shines more directly and intensely than it does in temperate zones. Since it isn't a problem here, I think that just emphasizes that the OP isn't true.

Love bugs, on the other hand, will erode paint off your car if you leave them on there too long. Which reminds me I need to wash my windshield...

[rangerdog]

It must just be Texas. I think they have perpetual black clouds......

[Towknie]

Originally Posted by Aud 1

(Or possibly being seen in a wet t-shirt by your neighbors.)

And this is why we have city ordinances and HOA covenants against washing our cars in our own driveways. It's sooo pedistrian to have a bunch of people prancing around in wet t-shirts splashing each other with soapy sponges.

Seriously though, we're not allowed to wash our own cars here. Brings down the curb appeal or something like that even though all our houses are rear entry with the driveways in the back.

[Alchemy]

Originally Posted by Delta-V

Water spoting is generally caused by letting the water spots dry out, leaving behind whatever dust is contained in it. Not sure how much a problem the magnifying effect would be since the focal point surely isn't right on the surface.

Water drops in air can promote galvanic corrosion; that's about the most likely problem you'd have with a car, and engineered automotive coatings took care of this problem a long time ago.

Water spots are mostly salts and stuff that was already in the water, not dust so much. You normally get a small amount of salts left on the car from the water, just not enough to see it. The droplets evaporate, concentrate the salts, and leave it there thick enough to be visible.

Since they're salts, they can be corrosive, so if you leave them on the surface long enough they will pit.

Rainwater is environmentally-distilled water. Rain doesn't cause spots because there's not enough salt in it.

[Delta-V]

Originally Posted by Cervus

Down here it's not uncommon for it to rain while the sun is shining.

Same here. Last year while driving home, I was in a torrential downpour and not only did the rain reduce visability, but bright sunlight reflecting off the now-wet road was blinding. The storm cloud occupied maybe a few square miles, not enough to blot out the evening sun.

Originally Posted by Alchemy

Rainwater is environmentally-distilled water. Rain doesn't cause spots because there's not enough salt in it.

But it does gather up whatever dust is already on the car and cause spots that way.

Originally Posted by Alchemy

Rainwater is environmentally-distilled water. Rain doesn't cause spots because there's not enough salt in it.

Not in areas with significant air polution. That water can pick up all sorts of "stuff" on its way down.

Remember the term "acid rain"?

Originally Posted by Towknie

Seriously though, we're not allowed to wash our own cars here. Brings down the curb appeal or something like that even though all our houses are rear entry with the driveways in the back.

I think I'm going to throw up...

I've always hated HOA's, but you can't even wash your own car on your own property?

I must be very lucky to live in a city/neighborhood where there are no significant problems with what the neighbors do on their property, but also no significant restrictions with what I do on mine...

-Tim

[Gayle]

Originally Posted by Towknie

And this is why we have city ordinances and HOA covenants against washing our cars in our own driveways. It's sooo pedistrian to have a bunch of people prancing around in wet t-shirts splashing each other with soapy sponges.

Seriously though, we're not allowed to wash our own cars here. Brings down the curb appeal or something like that even though all our houses are rear entry with the driveways in the back.

I find this soooo hard to connect with the Frisco I knew with one stop light and a nursing home. I wonder what the old timer's make of it? They've probably moved to Salina or Dorchester to escape the city...