[Milliwatt Rob]

Owners who live where no road salts or winter corrosives are applied to roads need not respond. Indeed, you are to be envied.

But for those of us who live in the salt belt, all that aluminum under the car has me concerned. While I intend to not use the car as a daily driver in winter, there is always the possibility that it will be necessary to do some driving in adverse weather on treated roads.

Has anyone had any kind of anti-corrosive treatment applied to the underside of their car? Does the car come from the factory with any kind of anti-corrosive coating?

We have a shop up here advertising that they will treat the underside of any vehicle with a clear, thin anti-corrosive fluid that should be reapplied every 18 months. I intend to look into it.

 

[53Vette]

This topic has been brought up a few times already.
Most people say no.

 

[glen e]

Undercoating was popular with dealers for profit in the 80’s and then for warranty, mfrs got smart snd started protecting the cars better. Unless you are in some heavy salt area and plan on dying with the car, id save your money....cars are much better now.

 

[cutnout]

If it aluminum or a good stainless then rust will be a lesser concern. cutnout aka Charlie

 

[Chip]

If it aluminum or a good stainless then rust will be a lesser concern. cutnout aka Charlie

Charlie; While aluminum does not rust, it can & will corrode. The degree to which it corrodes depends on the alloy used. Most marine alloy applications are in the 5XXX alloy system and provide the best resistance to corrosion. Most all auto sheet applications are in the 6XXX family which provides very good strength properties, but are subject to corrosion when its exterior oxide is removed or disturbed. I am not familiar with the alloy used in the cast structure used underneath, but would guess a protective coating applied to it would not be a bad thing as long it was not an alkaline based solution. A coating would also be beneficial to all the steel fasteners that hold everything together.

 

[cutnout]

Charlie; While aluminum does not rust, it can & will corrode. The degree to which it corrodes depends on the alloy used. Most marine alloy applications are in the 5XXX alloy system and provide the best resistance to corrosion. Most all auto sheet applications are in the 6XXX family which provides very good strength properties, but are subject to corrosion when its exterior oxide is removed or disturbed. I am not familiar with the alloy used in the cast structure used underneath, but would guess a protective coating applied to it would not be a bad thing as long it was not an alkaline based solution. A coating would also be beneficial to all the steel fasteners that hold everything together.

I agree as I am use to 2024 and 6061T6(best memory) and corrosion was manageable. I wont use my vette in the salt even if it was coated and I would coat the underside if I lived in the north climates. Thanks for the clarification of mat'ls. Charlie is cutnout

 

[jsvette]

Another issue with aftermarket undercoatings (besides the extensively discussed high profit, low need if any, etc) is the concern that a couple of unintended consequences could follow the treatment: blockage of necessary drain holes and improper application resulting in creating moisture capturing pockets.

 

[Milliwatt Rob]

I was not considering an asphalt based, permanent undercoating. Rather, a thin oil based fluid film type spray coating that is reapplied annually.

 

[regguy1]

This stuff is good, you could do a DIY job with it
Fluid Film® | Corrosion Preventative, Lubricant and Rust Inhibitor


The C7 frame is coated at the factory, the front and rear sub frames where engine / trans mount are bare aluminum.

The main frame black coating can be seen at 1:40 point in this video segment:

 

[regguy1]

You can see the black coated frame here on mine, A frame is bare alum.

 

[Jerry U]

Owners who live where no road salts or winter corrosives are applied to roads need not respond. Indeed, you are to be envied.

But for those of us who live in the salt belt, all that aluminum under the car has me concerned. While I intend to not use the car as a daily driver in winter, there is always the possibility that it will be necessary to do some driving in adverse weather on treated roads.

Has anyone had any kind of anti-corrosive treatment applied to the underside of their car? Does the car come from the factory with any kind of anti-corrosive coating?

We have a shop up here advertising that they will treat the underside of any vehicle with a clear, thin anti-corrosive fluid that should be reapplied every 18 months. I intend to look into it.

The aluminum and other parts are coated with corrosion resistant products by the factory. If you add anything it is my understanding you lose the factory warrantee.
Here is what the Owner’s Manual, page 10-73 says:

Underbody Maintenance (page 10-73)
At least twice a year, spring and fall, use plain water to flush dirt and debris from the vehicle's underbody.
Your dealer or an underbody car washing system can do this. If not removed, rust and corrosion can develop.

This comment from a person discussing Ziebart said they no longer provide a “lifetime” rust guarantee and you must pay about $100 yearly for an inspection to keep the policy (warranty) in force. Therefore you've just paid $1500 for a 3-year warranty (from the factory 7 years to 10 years) or $500 per year. Also it should be noted that if you do use Ziebart, it would void your factory warranty.
I lived in North East Ohio for 6 years and had a 260Z that I didn’t drive in the winter and a CJ-5 Jeep. I had the 260Z, Ziebarted. Despite not driving it in the winter it rusted on bottom of the front fenders! I would bring the CJ to a hand held car wash all the time and sprayed the underside as well as the body. I brought the Jeep to a fellow who sprayed undercoating under the Jeep every other year. The floor rusted and I had to repair some large holes! The undercoating just trapped water between itself and the floor!

 

[SwisStingray]

For more than 25 years I'm used a liquid wax for car bodies cavities, but for the chassis underside elements, all the suspensions elements and all the exposed parts !
No possibility to see the wax going too dry to permit humidity to go through.
This product is slightly brown but stay transparent and you can simply spray it with a little garden spray bottle.
Since my first use I have never seen any corrosion on the treated parts and we have very salty roads in winter over here.
Many guys and professionals were/are surprised when they see the product type I use to protect my cars undersides elements, more over some guys don't understand why I do that but those elements are never protected from factories which prefer to stay treating the undersides only :roll eyes:

99% have never seen my cars undersides but I'm only satisfy when I know that I have done my best to keep my cars in mint condition
I'am so obsessed that when I drive them I wipe the pads dust off the wheels at every opportunity I can along my trips

 

[LT1xL82]

I was not considering an asphalt based, permanent undercoating. Rather, a thin oil based fluid film type spray coating that is reapplied annually.

If you decide to do something, I think you are on the right track. Asphalt based is yesterday's solution and I would not do it to a Corvette on a bet. Thin "oil" (not really) fluid coatings seems to be today's standard. I have had Krown Rustproofing applied to my Suburban for 6 years. Costs about $150 each time...Not cheap! But with the "salt" et al used on the roads in north central New York, the Suburban as held up well. A few notes: 1) It drips for awhile after the application 2) It is a magnet of dirt.

An older Suburban that I seriously rustproofed with the thick black rustproofing/undercoat started having serious rust related failures (fuel tank, brake lines, drive shafts, mild to moderate body panels and frame...). When the stuff starts peeling from the surface it becomes a pocket for moisture/salt/sand.

I do not plan on using anything on the frame of the Corvette...and do plan to keep it off the roads unless they are clear of salt/sand. The typical Krown application drills varies holes to gain access into fenders/doors/tailgate... I don't know if they do this on Corvettes...but I sure would not let them!

BTW, Krown sells the product in aerosol cans...maybe going that route for select areas you feel need it is an approach to consider.

 

[jsvette]

SwisStingray my Porsche came from the factory with a wax coating on the entire underside. If I were to ever feel the need, which I don't, that would be the route I would go. When I lived in Michigan where salt was generously used on the roads during winter, I would bring my cars into my garage and thoroughly rinse the underside down with warm water. Luckily my garages were heated and had drains. In 18 years there I never had any issues of rust even on some of my classic cars. But it was a hassle to make sure that I had the time to do a good job rinsing off all of the salt from everywhere.