Better to wash dry road salt off or leave it on?

[Omahaug]

Something I've always wondered is whether it's better to leave dry road salt on the undercarriage or wash it off quickly?

In other words is exposing it to short term moisture by hosing down the undercarriage with straight water to dissolve the salt and dilute it, better than leaving dry salt on?

I always thought that it was best to go wild and dilute it all off and that even if it's wet afterwards, it would rust less than salt left on that becomes wet and dry over a longer period of time. Was I wrong? What's the least likely way of creating more rust?

 

[bvance554]

Are you suggesting this layer of salt is acting as a rust inhibitor? The salt is going to absorb any moisture in the atmosphere and continue to rot your vehicle from the inside out. Wash it off when you can.

 

[Rolla07]

If your car sits outside in freezing temps the whole time in winter, id leave it alone..unless you are bringing to a car wash that sprays underbody well..

 

[Merkava_4]

Originally Posted By: NoNameJoe
What's the least likely way of creating more rust?


Rinse the salt off with fresh (unsalted) water. No need to dry.

 

[Bgallagher]

I posted something similar to this today. My thought is if the weather is warm enough it is worth getting rid of the salt. At the very least a good spray of water on the body and undercarriage will make a big difference

 

[Artem]

I think the car will continue to get soaked in salty water for months to come. Every time it will rain, you'll be driving through a salty soup, splashing that junk all over the car until it finally washes off with repeated rain and when 95% of the public actually wash their cars in the spring.

I think it's a constant battle, which is why undercarriage protection costing seem to make the most sense, if you're serious about protecting that car from rust.

 

[ford46guy]

The other day I was driving on rural roads in Upstate NY. I was driving in a cloud of salt. My car looked white afterwards. This substance likely goes everywhere, behind panels and into frame recesses. The $10 undercarriage washes are useless, I've tried a bunch and salt always remains. A good hose wand is somewhat better. A sticky undercoating (fluid film, krown, even oil) is your best defense. Don't forget where you can't see.

Water alone may not be enough, i think you need some good detergent or neutralizer to get it off. I can spray my car for an hour and the salt residue sticks to the panels.

 

[Bluestream]

OIL spray your undercarriage and never worry about salt again

 

[ford46guy]

Originally Posted By: Bluestream
OIL spray your undercarriage and never worry about salt again

Yup, I spent some time removing rust, converting it and painting it with a few coats of rustoleum on the explorer. I am testing fluid film, Atf and gear oil on different sections. Not a spec of rust so far, just a matter of one lasting longer than the other.
Even if a bit of surface rust forms it is manageable vs bare metal that will get destroyed.
The truck came with a rubberized undercoating, trust me, it is not a good idea. After one of the torsion bars broke I started really paying attention to rust.

 

[KrisZ]

Originally Posted By: Bluestream
OIL spray your undercarriage and never worry about salt again


Amen!

 

[Cressida]

It can never hurt to complain to the local city or officials that are doing all of the road salt. Where I live (and in many other parts of the country) the city will salt roads whenever there is a light dusting in the forecast (like tonight - less than 1/2") even though it will be above freezing by 9-10am the next morning. It's just not always necessary and they tend to go crazy with the stuff.

I can understand the employees like the double time pay but it destroys vehicles and runs off into the fresh water supply. The University of Minnesota has completed long term studies showing the upper Mississippi now has more salt in the water and it is directly attributed to all of the road salting run off.

We used to be taught to leave early for work and slow down on the snow days, but now that doesn't seem to be an option for the public so just pour on the road salt.

 

[larryinnewyork]

ford46guy,

Careful spraying ATF or gear oil.
Reason: It can soften any rubber components and may short-out electrical connections.

I use Fluid Film.
Read there web-site about advantages.

I think some Posters made good points about the difficulity of washing the salt off.

I now plan on just going for a Spring time drive during a rain storm to wash off any undercarriage salt.
For my situation, that should be fine.

 

[CourierDriver]

discernment /dɪˈsɚnmənt/ noun
Learner's definition of DISCERNMENT
[noncount]
: the ability to see and understand people, things, or situations clearly and intelligently
His lack of discernment led to his disastrous choice of business partners or to remove salt that could rust his auto.....

 

[eljefino]

Salt attracts moisture. If you ever get salt on a shoe for example you'll notice it takes 3 days to dry out inside.

If you manage to get dry flaky salt leave it alone! It's better than the wet stuff that's chemically active.

It's up to you to watch the weather. If it looks snow-free for over a week I'd consider washing the car. But the roads will still have that sheen of salt.

If it rains and washes off that sheen, and you managed to miss having the rain wash your car, go for it. Pretty hopeless here.

 

[ford46guy]

Originally Posted By: larryinnewyork
ford46guy,

Careful spraying ATF or gear oil.
Reason: It can soften any rubber components and may short-out electrical connections.

I use Fluid Film.
Read there web-site about advantages.

I think some Posters made good points about the difficulity of washing the salt off.

I now plan on just going for a Spring time drive during a rain storm to wash off any undercarriage salt.
For my situation, that should be fine.

I paint the oil on the hard parts of the frame and diff with no rubber. Rocker panels, undercab, fuel tank, etc. FF everywhere else. Just want to see what lasts longer.

 

[HerrStig]

Up here the authorities now spray a liquid on the pavement ahead of storms to keep packed snow from turning into ice. It's murder on steel.
The Swedes did a study a while back which showed that cars kept in heated garages rusted faster than those kept out in the cold because the cold reduced the activity of the salt.

 

[MNgopher]

And in reply to Cressida, guaranteed you will be in the minority complaining about too much salt being used. I say that working for an organization that uses 10's of thousands of tons of salt yearly on its roads. Everyone is an expert on snow and ice removal and isn't afraid to share it with their politician...

We get 10s of calls every snow and ice event. The complaint is nearly always that we didn't use enough salt.

It is not to our advantage to dump more than is needed. We don't have the budget. We currently buy six figures worth of salt per year. It's not cheap. We don't get extra time unless it's over 40 hours in week or weekends/holidays. We don't like to hand out overtime because that means something else has to give in the budget.

At the end of the day, the public generally demands the ability to drive in excess of the speed limit immediately at the conclusion of snow or ice events on bad tires. If they can't, we did a bad job per the politicians we work for...

It's all about expectations. I drive 4×4 vehicles with snow tires, so my expectations on level of service are different, but the general public disagrees.

Not advocating using more salt (far from it), but pointing out its easy to say we always use too much since it's in our financial interest... believe me, on the management end it isnt...

 

[Omahaug]

So it's not like I think the salt is going to do good sitting there. It's what other people are saying, I was torn on whether the salt is totally inert sitting there or if the rust due to water (in the absence of salt) was worth it.

For what it's worth I wash the undercarriage as soon as I can. I get down and dirty with a long hose wand that makes it very easy to hit every part of the undercarriage.

I always wondered through whether the water makes more damage than just leaving the salt on in the absence of water. Water by itself does cause rust as well no?

 

[Michael_P]

As others have said, oil spray. You can use commercially made rust preventatives or make your own. However, DO NOT spray oil on now. Wait til spring after the road salt is washed off. Then thoroughly spray off your undercarriage and door pinch welds with water. Let it dry for a week, then apply the oil. If you do it now, you will encapsulate the salt to the metal, causing a bigger problem. Most liquid road de icers contain used fracking fluid which consists of brine, sulfuric and hydrochloric acids as well as a myriad of other chemicals. There is usually some for of sugar in it as a tackifier. If you drive over it while it is still wet, it will penetrate layers of metal. And to think I have seen people tailgate these de icer trucks when they were applying de icer. Thats a sure fire way to ruin a core support. Driving style and habits can affect how your car may or may not corrode.

 

[Omahaug]

I always wanted to spray oil but I feel like it causes more problems than it could solve? The underside would get all caked in grime from dust soaked into oil wouldn't it? Like one big engine oil leak but all over the bottom of the car.

I don't even know what it would do to the hoses and rubber (although Fluid Film is safe I believe).