Used compressed air as much as possible - good if you have an opening for the debris to exit. You really don't need to overdo the prep with Woolwax or Fluid
Film. Different if you were using a paint type product.

Here's what I did. Don't skimp on PPE

https://www.toyota-4runner.org/3618447-post36.html

Your frame looks as good as my ‘07 Limited V8 with 172k. Primarily some surface rust and rust at the welds but no structural rust. I had Wool Wax Black applied a couple weekends ago. A local rust proofing retailer did it for $180. I am vey pleased with the outcome. He uses both Wool Wax and Fluid film but prefers Wool Wax as it is a little thicker and he says only needs touched up every 2-3 years whereas Fluid Film should be done every year....and FF smells really bad vs. Wool Wax. He says not a lot of prep is needed with either product. Just knock off the loose rust by tapping with a hammer and then wire bush the smaller loose pieces. Took him a half hour to prep then an hour or so to undercoat and spray in the doors etc.

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Paint-like rust inhibitors can trap rust. They don't wick into small cracks like a thin oil and once they cure water and salt can get behind them. Some people have luck but I've seen enough failures to make me wary. What I did to mine in the link, fair amount of work but less than what you're describing here, and a lifetime coating other than touching up the bottom of my diffs every 3 years or so. Would still wire brush the loose scale - Ultimate oil undercoating guide (DIY Waxoyl)

Yea thats what I am thinking. I feel it may be best just to go with a full coating of fluid film and call it a day! Appreciate the link.

Agreed! Wool Wax, Fluid Film and from what I can tell your Ultimate oil all work off the same principal. They are nota paint like coating (like POR 15). They are organic, self healing and never cure into a rubber like coating thus hastening the rust problem. I bought a used Tundra awhile back that had Zeibart undercoating and there were a lot of areas where the undercoating looked like there were big bubbles of rust under the coating. The first owner took it in every year for a touch up but I think it exacerbated the rust issue in that 2011 Tundra frame.

Has anyone ever tried installing sacrificial anodes onto the frame (inexpensive and easy to get from boating supply places or amazon)?

It'd probably have to be stuck in a spot where water collects or tends to pool in order to do much good, but I'm kind of thinking that for $20 or so it can't really hurt anything.

Also, a trick I've used on cast iron pans to remove surface rust is to scrub with a wad of aluminum foil. Again, I don't know if it actually creates any galvanic reaction in the Iron, but it's an effective abrasive and once again it's cheap and has no real down side.

You might even be able to stuff fist-sized wads of aluminum foil into un-paintable cavities on the frame to get some galvanic protection. Probably re-check after a few days of driving to see if they're still there.

This is the solution that will work without 80 weeks worth of prep. Not the prettiest, but a driver quality solution.

I had the Waxoyl treatment done to the underside of my new 4Runner the week after I bought it. They don't treat the inside of the box sections of the frame though and that's where the real issues begin. I highly recommend getting some sort of rust inhibitor sprayed inside the frame when the vehicle is new. Waiting until the rust has started to do something is foolish.

The problem with a 4Runners as opposed to a Tacoma like I came out of is that the Tacoma frame is only partially boxed. (And guess where they rot out?) This makes coating the box sections on a Tacoma relatively easy.

The 4Runner frame is pretty much completely boxed, so access is a bit trickier. I'm experimenting with a very different internal coating. Let's just say it's Toyota approved - for another Toyota vehicle. Only time will tell how well it works, but it's got to be better than nothing!

That thread has a link to the gun and wand I use to spray inside boxed frames, fits through all the holes and is multidirectional spray. Replacement wands for that model are also available ~$20 with shipping. Surprised Waxoyl doesn't spray inside frame for what they charge, but it is def a pita getting a hot mix to flow through a wand, esp at cold temps. Another reason to DIY. What are you coating with?

Don't be shy, tell us what the "very different internal coating" is !!!!

I just done this a week ago!!
I got in with a wire attachment on my grinder and every flat surface pretty much wiped till no rust, or every big loose chunk was off.

I then used a regular primer on the bare metal, or metal with some rust etc.....

And on top of that added bedliner black, both primer and bedliner was a spray paint bottle.


I have videos and pictures. I’ll maybe link my Instagram and post there? I just don’t want to upload here. Or text my number.


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I don't want to get in trouble for having it in there. Re-read my original post. There's a pretty decent hint in there. Wink, wink.

Unless the secret recipe is ground Sumatran rhino horn and cocaine, the odds of you getting in trouble for posting about it on an internet forum are about as good as my odds of winning Powerball this week. And I haven't bought a ticket in years... But anyway