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WD-40 into body panel drain holes

Somebody recently told me that to help prevent rust and corrosion in body panels etc. to spray something like WD-40 into the drain holes (using the straw) of the doors. Also to remove rubber plugs to body parts spray WD-40 in the holes and then replacing the plugs naturally. He said that he did that for his old pickup and never had a problem with rust coming through. That he did 4 times a year. Sounds like a great idea to me. But thought I would post it here to see if there were any contra thoughts.

I’ll bet he’d get the same results just clearing the drain holes and inspecting the rubber seals 4 times a year.

Most all new cars (last 10+ years) don’t need this. I also wouldn’t spray it into doors, could cloud the windows.

Back in the day, auto manufacturers didn’t do much in the way of preventing body corrosion. So something had to be done to seal the metal from corrosion. Back then there were Ziebart and Rusty Jones anti-rust packages offered. But I don’t see too many of these businesses around anymore. Or people would spray the inner panels with 10 weight motor oil.

But todays vehicles have aluminized/galvanized body panels where rust through isn’t much of a problem anymore. So on an older vehicle, anything that seals the metal panels will help to prevent rust.


Yep agree. If you must though, there is a product made by 3M I believe, available at NAPA or others, just for interior surfaces. Its is a clear waxy substance that you spray on and it stays pliable to prevent rusting from the inside. To do it right, you take the door panels off and spray the lower door portions. Not worth it anymore in my book though. By the time the doors rust, the frame is shot.

FORGET WD-40…It is just kerosene with some sent agent added. It is 100% evaporative and leaves no protective coating. Your idea may be good, but use a product like Boeing T-9 rust protective spray available in Marine supply stores.

It’s Wishful Thinking. Put The Money Not Spent On Ineffective Rust Prevention Into A Jar And Keep Adding $$ For the Day You’ll Buy New Body Panels That Come Attached To A new Car.

I had rust-through on a can of WD-40 and the contents leaked out.


“It is 100% evaporative”

Almost. It would be a better product if that were true. It does have some heavy oils mixed in and they can gum up the works of some equipment.

However you are right, “FORGET WD-40.” It is good for displacing water (but not keeping it out) and it will work as a solvent, until it starts trying out and it leaves a sticky mess.

WD-40 will gum up and get sticky. Then in turn it will collect debris that holds moisture and then rust may appear.

That stuff is also used to remove sticky stuff, so it may damage whatever sealant or rustproofing that may be in those areas. Use it if you have an old pickup…

That Is My Concern, Too.

You can void the factory rust-through warranty on a car by adding your own rust-proofing. Besides plugging drain holes, as many thicker substances can do, you do run the risk of an adverse reaction with factory sealants, as PDV2 points out.


I remember reading somewhere that SAAB used to recommend this in their owners manual, squirting used motor oil into access holes drilled for exactly that purpose. I’m looking for the article, used to belong to a club with a newsletter for SAABS. I can’t see that it would hurt maybe messy. Rocketman