The belief in spring rust

[Donald]

So rusting like any other chemical reaction is temperature dependent. So not much rusting happens in the cold winter unless stored in heated garage. So when it gets warm and the salt is there from the winter, the rusting begins.

If you spray with FF or CarWell in the spring, it pretty much coats all the areas where rust is likely and the salt is not an issue. It either gets blown off during the cleaning prior to spraying CarWell or the salt is dealt with by the spraying of CarWell.

By winter not much of the product is left because it got washed off but it does not matter because the rust will not happen in the cold winter and the vehicle will get treated again in the spring with FF or CarWell.

CarWell company suggests doing the treatment in the spring.

I think there are holes in my story, why shouldn't a good rinsing of the undercarriage do almost as well as a treatment like CarWell or FF??

I would like a thicker product to spray on the undercarriage, but the normal CarWell product in body cavities.

I would feel much better if most of the treatment was still there the next spring

 

[Ethan1]

Exactly. Rubberized undercoating is the best product for the undercarriage and FF is good for the insides of the doors, unisides, etc.

 

[Rand]

Think it really depends on undercoating.

in MN or BC where its cold always its alot different from Virginia climate.

 

[fdcg27]

The spring also brings rain.
Driving in this rain washes all of the wintertime corrosives out.
I personally think that aftermarket rustproofing is of little or no value.
A ruster will be one with or without some aftermarket treatment while a sound design made of proper materials will do just fine without.
YMMV

 

[oilpsi2high]

Originally Posted By: Ethan1
Exactly. Rubberized undercoating is the best product for the undercarriage and FF is good for the insides of the doors, unisides, etc.


You have to do the rubber undercoating when the car is new, otherwise you're just making any rust worse.

I mix bar/chain oil with a solvent in the spring and spray the undercarriage. Best option for a used car. My car has seen 10 winters in upstate ny and this definitely slows down the oxidation process.

And yes, it does rust faster in the spring.

 

[Olas]

A wire brush attachment for your drill or grinder if any rust is present, then waxoyl and a paintbrush what you can see and Schultz gun what you can't.

 

[JHZR2]

Apples and oranges are being discussed here.

Spraying anything, especially rubber undercoating, on dirty, rusty, or salty surfaces is a recipe for disaster. Those rubber products are not necessarily always impervious, and can trap water against a surface, and also hide damage as it is occurring. It is the least favorable method, except for OE install on pristine surfaces, and potentially underneath the paint.

You don't spray oil on a salty surface, where there is no salt solubility in oil, and expect a good outcome. This is contingent upon reasonable cleanliness and then the oil's ability to creep into crevices where water would otherwise sit.

Sure it's warmer in the spring, and there is lots of rain... The rain can do good, by rinsing, and also not that good by forcing salt in deeper. Once it's there, it will hold its own moisture. You want to prevent it from getting there to begin with.

I'm personally not a believer in doing a spring coating, rather, a late summer or even a fall coating.

You really need to be smart about use of waxes vs oils, waxes even that are claimed to be self healing can dry and can trap moisture. But they can be much more wash resistant...

 

[The_Jeff]

Anything wax-oily that sticks via viscosity should be applied in late fall so the cooler air helps it stick.

Where I live there are snowbanks all winter and at least a passing chance of black ice, so the roads need/ get a film of salt pretty much all the time. No way to wash one's car with water and have it not immediately un-done.

 

[KrisZ]

I also oil spray in late Summer or early Fall for two reasons: 1) the underside will be as free from salt as it can be through regular cars washing and driving during rain. 2) warm temperature will aid in capillary action.

With the vehicle treated just before winter, there is very little chance of salt penetrating seams and crevices as these places are already coated with oil. Any salt buildup will be on the exposed surfaces, on to of the coating, which will easily be washed off during Spring/Summer.