Piston Slap: Hands-on Questions for the Touchless Car Wash?

Sajeev Mehta
by Sajeev Mehta
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piston slap hands on questions for the touchless car wash

Seth writes:


I’ve admired your columns from afar for years, as a non-commenting TTAC reader. I especially appreciate your tenacious appreciation, possession and maintenance of cars you love. My automotive life is not nearly as exciting or robust.

While I love my cars, with two small children, a wife and a full-time job, I only have time and money for two at a time (his and hers). I aim to keep them for at least 10 years each. So, I obsess over the scratches and dents knowing I’ll be stuck with them for that long. Ridiculously, I even worry about scratches from washing them.

Which brings me to my question: What’s the best automatic car wash to use to minimize paint damage?

I’ve heard it’s best to hand-wash cars, but I don’t have time for that. I’ve seen the repeated reuse of “non-abrasive” towels from multiple prior cars by staff at detailing centers that hand wash it for you. Numerous websites demonize both touchless high pressure water spray and traditional brush-type machines, saying how each leads to paint damage.

Can you please help put this obsession to rest?

Sajeev answers:

Great question!

My thoughts on the matter are similar to this pro-detailer’s blog: the brushless/touchless/laser car wash is the best choice for you. It’s certainly not ideal, as it won’t clean as deeply as the brushed models, but those machines store dirt from previous vehicles and I doubt most car washes clean the brushes regularly enough to please the likes of our Best and Brightest.

Touchless car wash places have two other likely problems. Water is recycled and can become super salty after a wintery week. It is filtered, but to what extent? Then we have high pressure water essentially sandblasting the car’s current grime into the paint. They can’t match a carefully trained, human touch and a clean garden hose. Provided you have the time, the ideal weather, and your part of the country isn’t rationing water!

So what’s the lowdown? Always keep a regular coat of polymer-based wax on the paint, stick with touchless car washes with high quality filtration practices (check your local or state regulations on this) and you’ll be fine for 10+ years. Not to mention your vehicle’s next owner will gladly pay you extra for your effort!

Editor’s Note: Sajeev mentions paint and other visible surfaces, but there’s a lot of bare metal under your car that is just looking for the first opportunity to rust.

If you live in an area where salt is used on the roads and either 1) the temperature fluctuates around the freezing point, or 2) you keep your vehicle in a garage, it’s just as important to spray the underside of your car during the mild days of winter.

When road salt is “frozen”, it won’t cause corrosion. However, when that salt-filled slush that’s been packed to the underside of your car does finally melt, that’s when salt-triggered corrosion can really take hold.

So, if you want to do yourself a favor (and a favor for your mechanic), do this: As soon as you run through the automatic wash, drive your car over to one of the self-service wand wash bays, drop a couple bucks in the meter and spray away all that semi-frozen salty slush from the underside of your car.

[Image: Shutterstock user DedMityay]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Sajeev Mehta
Sajeev Mehta

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  • Burgersandbeer Burgersandbeer on Nov 07, 2015

    I'm more worried about the wheels than the pain at any wash where the car is driven through. Especially so if you have wide wheels.

  • -Nate -Nate on Nov 08, 2015

    A very informative thread here . Some one commented on Polymer based wax , I discovered it by accident 20 + years ago and am almost out of it . Granatize brand . What brands are available now affordably ? . like @ Pep Boys , Kragen etc. . I prefer a clean car but often wind up with it dusty after a short time . My Brother's various vehicles are dirtier than anything you ever saw in a Junk Yard , this causes me grief , he makes fun of me washing his windows so I can at least see out =8-^ . -Nate

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