Alright Old Dogg, I have emailed WD40 to find out for sure.

 

I will look at your links but facts are facts.
You have to rub and scrub dirt, chemicals, salt water residue/dried salt chrystals ect with soap and water to remove. Under the vehicle, in complex areas and voids you cant wipe or touch water will collect but eventually dries.

A mix of oil and water will take much longer to dry and a mix of oil, salt and water will take even longer.
All will eventually rust but which do you think will corrode first and fastest?
Dry metal or the others with a mix of dirt oil and salt?

This is why the Military (Navy) stopped using it to protect complex metal shapes...even in electrical applications.

A better alternative would be something that dries hard not tacky or stickey, either water repellent or water proof. They make things for the application but they cost more for a reason. Sometimes short cuts will cut you short.

If you write or call WD40 do you really think they will discourage you from using thier product?

 

No way I would spray it all over the bottom of the truck, but I did squirt some every once in a while in the weep holes in the bottom of the doors where the sheet metal is rolled and crimped on my 2001 F150. Kept that area looking like new for 8 years. My buddy who got his a few months after mine, who didn't do it, has rust showing on the outside of his doors now.

 

I don't know how common it is in Virginia or wherever the OP is from but up here in Ontario, we use some stuff from Krown, nice creeping rust preventive oil. This stuff goes on light colored and lasts up to 2 yrs really. For $120 and 2 yrs, well worth it. Plus they shoot this crap in the doors, sills, everywhere. Stopped the rust at the door/tailgate bottom helm? stopped it cold. Seems like alot of work wd-40'ing the truck every couple of weeks.

 

Are you lost or something?
Are you a converted Chevy man, now a FORD man?

Oh... I see, from VA.
Must be from West VA!
--Just kidding.--
My cousin (from Richmond) never stops tooling on W. VA.
Kinda like he tools on myself & the family for being 'Yankees' up here in New England.
Glad to know we have Chevy people in our forum.
(although I wouldn't be caught dead in a Chevy Forum)
HEY, I have a question for you Chevyman.
Almost every Silverado I see on the road has one front parking light out.
What's up with that?

 

obviously dry clean metal will be the best, but if its a daily driven truck lets be honest are you going to go under every day and scrub it with soap and water? i dont think so. so a good option is too keep that wd40 on the metal. it keeps it lubed and rust cant form on it till it evaporates. i will see what wd 40 company explains to me.

we rarely see salt here in va because we dont really get snow, but i dont know what happened this year we got a ton. so usually im not talking about combating salt just using it to keep the undercarriage clean which i believe it does a good job of.

 

Got the email back from WD-40. Apparently it doesnt harm anything but doesnt protect either.


"Thank you for contacting WD-40 Company regarding your application. WD-40 will neither harm or protect a car's under carriage. WD-40 will wash off too quickly to provide any benefit.

Thank you again for contacting WD-40 Company. Please let us know if we may be of further assistance."

Best regards,
Eva Zabowski
WD-40 Customer Service

 

now we know...

 

thats a pretty short and kinda lame reply wd40 sent you... I would have thought they'd of given you some more info that had some technical stuff in it

 

As long as it's not sprayed in a void or crevice where it and water trapped never get air and dry there is no problem.

I travel and have lived many places. I currently live in VA but my truck goes everywhere north, south, east and west. I was trying to tell the OP that there are rust preventatives specifically for undercarriage, crack and crevice protection but they cost more for a reason.
It is quite a bit of work to spray all over underneath with WD40 but it will eventually cause more problems than it fixes. Sometimes cheap things look good in the short term and then down the road the real expense comes.

Maybe if you use the liquid and apply with a rag or paint brush but just to spray it all over the place is asking for trouble down the road.

Here in southeastern VA we dont get much snow but when we do they overtreat the roads with salt and sand and since im near the ocean I often get salt spray or sandy salt all over my truck. All I do is a fresh water rinse, scrub what I can reach in the wheel wells, use some sort of dressing and keep it moving.

If you add up what you spend on WD40 and the time spent fooling around I bet you spend more than to get it done correctly with the correct materials or to just replace rusted parts when they start to fail.

Did you really think they would openly, on the internet invite lawsuits?

 

alright ill just rinse it with fresh water then and save my money.


should i spray degreaser and rinse or just use fresh water.

 

When Needed...
Degreasing, cleaning, inspecting, dressing and/or an undercarriage preservatives are never bad under the truck.

 

would i need to regrease anything after. and what undercarriage dressing do you reccommend?

 

Notwithstanding what the WD40 folks said (quite terse.... no sales job there), corrosion is a chemical reaction and has less to do with being dry or wet then whether it is exposed to oxygen. This is why corrosion is also referred to as oxidation. Salt is a powerful corrosive agent, esp. when mixed with water.

WD40, from what I know, is used to repel moisture. It not only resists water, it displaces moisture. I use it to remove and slow progression of the surface rust I see on my underbody, including all axles, suspension parts, body mounts, etc. It provides a thin layer of protection which offers no permanent protection and washes off in the normal course of driving.

I have seen dust adhere to a WD40 coating, so I have no doubt it may attract some salt, but I'm not too worried, because by the time the salt adheres, the WD40 has dissipated. I'll rinse the underbody and recoat it.

In the future, I'll continue to use WD40 under the truck as it'll keep many components brighter and rust-free. IMHO, I'd rather recoat periodically than have a rubberized coating on all underbody surfaces.

 

Yep theres always two opinions on everything. The only way we will know for sure is if we did a test.