Cavity Wax rust prevention spray

[R/T's 4 R/P]

Does anyone have experience with 3M Cavity Wax as a rust preventative for getting in hidden areas, seams, etc.?
3M part number 08852
I've used other types but would consider this for some areas simply for the convenience of the spray can and disposable nozzle.
How far does a single can go?
Does it leach out over time?

[Dmod1974]

I actually used Eastwood's version of the same product on my car a little bit (might even be the same), but have used the 3M stuff on others as well.  Both work great.  A single can can go pretty far; you'll probably need 6 if you're planning to do inside the rockers, torsion bar crossmember, and frame rails.  It'll creep and settle eventually becoming a soft, solid state.  It won't sweat or run after that.

[tparker]

No, but I used the Eastwood product my self and the nozzle is pretty cool.

[JH27N0B]

I've looked into best rust preventative treatment sprays and Fluid Film seems to be about as good as any of them, is cheap and can be found easily including places like Menards, at least in spray cans. Fluid Film can also be bought in paint buckets to spray on with your own spraygun apparatus.
When I was restoring my T/A I was using Boeshield T-9 spray based on some recs on forums.
A restoration shop owner I knew swore by pouring clean Dexron into every nook and cranny, and said that prevented rust from ever occurring.
He said you'd have to park the car on a plastic sheet for a time since trans fluid would be dripping from various places for days, but afterwards you were all set.
I sprayed Fluid Film on the bottom of my new Ram after I bought it, and touched it up again this fall. I used just under 2 spray cans to do the truck.  Some places like the rear axle and driveline yokes have surface rust I noticed.  It's apparent that these parafin based sprays burn off from metals that get hot, so I am still seeking rust preventative ideas that are heat resistant.  But everything else is good as new, so far.
The Project Farm channel on Youtube does some pretty good testing programs comparing various things, and did a good video on these products, though not Eastwood or 3M cavity wax. I guaranty you that the Eastwood product is just one of the other brands relabeled and marked up, though I have no idea which one it is.
https://www.youtube.com/watch?v=lyWHF4NoNVk

[PLUM72]

If you want to protect those hard to reach areas, I think you'll need a couple products.  Fluid film is thinner and will run into the nooks and crannies.  A thicker product like 3m or Eastwood perhaps, even CRC Corrosion Inhibitor are thicker and will tend to stay in place on the inner vertical parts.   

[Dmod1974]

I would 100% not use Fluid Film.  Every fall, I spray a gallon of it on the underside of my rot box 99 Silverado to buy it some more time before it inevitably rots enough for the cab mounts to collapse or frame to crack.  It works, but it SMELLS like livestock and is extremely messy.  It will seep and run for quite some time, and during hot summer days you will see stains on the ground from it along with that nasty smell coming back strong.

It also collects dirt like no other and you will look like one of those ducks in the Dawn commercials when you have to work on it.

It's awesome for equipment and salt/plow trucks running here in the rust belt, but I'd never use it on a summer car that isn't a total beater unless you like a real mess and want your car to smell like sheep.

The cavity wax products dry much more solidly and have no odor after they initially "cure".

[MoparLeo]

Ziebart has been used by many auto manufacturers for years as an optional rust preventative.
https://www.ziebart.com/auto-care-services/rust-protection/rust-protection-services

[moparroy]

might be of interest

https://www.classiccarrestorationclub.com/video/rust-prevention-cavity-wax-034555/?utm_source=newsletter&utm_medium=email&utm_campaign=A6202

I did not use this BTW - I used Eastwood Black internal frame coating (careful this stuff is wicked - only thing I have ever seen melt clear coat) and once cured sprayed a product I like called Rust Cure 3000 all inside the frame and enclosed areas like rockers