I wanted up to open up a discussion on rust proofing our 4Runners and ask what do you guys do for rust proofing? Recently, I rinsed out the frame, did a full de-grease + wire brush and coated the frame with POR15 rust inhibitor. Most of the rust was just surface rust, but I'm hoping this POR15 application will keep any further rust at bay.

I'm considering taking the truck into a professional to get rust proofed (eg. Krown), but I was curious if there's any good DIY options. I can get the $10 Rust Check spray cans, but I think having a long nozzle with a good misting spray pattern is key. In addition to spraying the inner frame, doors, and trunk, does anyone have comments on what areas should be sprayed down?

I do occasionally offroad the truck and will regularly rinse out the inside of the frame in the winter. How does having a rust proofing wax on the inner frame affect this? Will the wax/grease trap water?

I used Eastwood interns frame costing for inside my frame.

Then on the outside. Where I had little surface rust. I used a wire wheel to sand it of and VHT CHASSY PAINT. Been holding up good and through out the NJ winter.

Been also using FLUID FILM to coat my whole undercarriage. Especially on the rocker pannel section.

You can also use Eastwood internal frame coating if you take the plastic pillars of when you open the door. And stick the nozzle in and spray inside the rocker panels. Let it dry and spray Fliuld film.

I had few serious rust spots. And I sanded it and used POR15 on those areas. With MONSTALINER on top.

Used a wire brush attached to an electric drill to knock the worst of the rust off.

Brushed on this rust converter.

Klean-Strip 1 gal. Phosphoric Prep and Etch-GKPA30220 - The Home Depot

Then painted with Rustoleum.

Cheap and effective. Here's pics of my initial test, the spare tire.

What I started with.



After sanding and Prep & Etch.



After painting.

I have VERY little rust since I acquired my rig outside of NE but I went nuts with fluid film and spray on undercoating last winter. The spray undercoat is junk so I've been pressure washing the frame and using this stuff. I'm impressed so far but the winters will tell how good it is. Easy to apply and very little prep work, scrape any rust off with a screwdriver to get up any loose chunks then apply.

https://www.semproducts.com/rust-and...gs/rust-traptm

Injecting the frame rails with used motor oil is by far the most effective undercoat for your money. I've had pretty good luck with Rustoleum Rusty Metal Primer and their paint. I apply a thick coat with a brush. A needle scaler from harbor freight is the best way to get that loose scaley crap off. Corroseal is also another good rust converter, though not as cheap as the Rustoleum. You can put it in a spray bottle. I plan to use it on the upper shock mounts.

I bought this air tool kit on ebay to spray used motor oil with bit of gear oil to underside of the runner including inside the frame. It was bit hard to find this kind of a oil spray gun (top left, red gun). One day, a Canadian seller listed this on ebay and I didn't think twice to by it. Cost $50 to my door.

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in the salt belt, brushing the old rust out and then painting it back is far to be enough.

What we do here is undercoat our cars with grease, as simple as it is, it is the most efficient way to prevent that frame from rotting. I also use pressure-sprayed used oil for door interior, rocker interior and so on. Underneat, special anti-rust grease I buy at my local canadian tire (rust check, the green one). Used motor oil for the undercarriage will wash-off too fast, use grease.

Adding about 20-30% gear oil to used motor oil (or even better penetrating oil) seems to keep the oil film for longer periods.

Thanks for the suggestions! I don't have an air compressor so was thinking of modifying a $10 garden pump sprayer with an extended nozzle. I wonder if it would be able to spray a thicker fluid like oil.

This thread is great! Thanks for the tips and keep them coming!

Look one in local CL. These pop up for cheap. Don't buy any off brand compressors or pan cake type compressors. Ideal size is 8 gallons but I am OK with 3 gal 125 psi tank.

A compressor is so useful when you have an automobile. Go for it.

I got a 8 gallon Craftman compressor for $20 in Louisiana CL. A parasite stole it from my front porch!

Also, a really good recipe for anti rust I've often seen here is used oil mixed with grease (and sometime a bit of transmission oil), but the thing is that you have to heat up your oil on your oven to dissolve the grease.

Does this have a name, or any way to reference it in a search? I sure would like to use my used oil!

I did a bunch of looking and research and i just bought Eastwood"s rust converter and rust encapsulator.

IMPO - a pump sprayer, only transfers thinner liquids / probably not oil or wax-oil effectively.
This is recommended as the DYI Fluid Film method:


Back in the 1970's - I had my car used oil sprayed, every fall.
- however, con is on the Ph level / used engine oil, has acid in it
I have sprayed Krown myself, decades ago / it seamed water soluble, and washed off too quick.
- gone from the wheel wells, in one months time
Now I stick to way-oil products / but vehicle metal has to be totally free of any moisture, for lasting protection.