What do you do to wash off the undercarriage?

I'm sorry but I have to disagree with that statement. My prior Durango ('99) frame was in almost new condition when I sold it after the exact same frame maintenance techniquie used on my 4R. My friends Tahoe is 11 years old now and it spends half its life in the salty ski country and rarely, if ever, does he wash the exterior let alone the underside and it is in very decent shape compared to mine. My company Ford trucks are all 15+ years old and are in great shape as well and these trucks never get rinsed off expect for by the rain on the road!

It seems like these 4R frames are 'high maintenance'. They can be prevented from rusting out, you just have to do a LOT more than you would to any other SUV on the market to fend off the rust.

It sounds like these frames need to be coated annually at a minimum for them to have longevity vs other frames. I just wish I knew how much extra attention these 4R's needed underneath years ago vs others. Oh well, live and learn as they say.

Just a garden hose and nozzle. Of course that's a pain in below freezing temperatures.

But the alternative from my past in consumer auto repair, is rust if neglected. That goes for every brand which I saw rotted out examples of regularly. I still have friends in the consumer car repair business, and they all say that all vehicle makes still rot out if neglected.

Using a garden hose with a nozzle to wash the salt off when the frame became white with caked-on salt isn't high maintenance. It's just common sense. It's also mentioned in every owners manual I've ever had, that it's important to wash off salt when the vehicle is operated in a highly corrosive environment.

I guarantee those holes in your frame didn't appear overnight. That's been rotting due to neglect for a long time. My advice is spend more time cleaning off the salt in the future, on whatever vehicle you have.

I'd take it in and talk to your local Toyota service manager, and ask for an evalutaion, and I'd also try to go up the chain with Toyota corporate, that is nuts!
Toyota should be able to figure this frame thing out, factory dip, then coat the frames!

PS my Bro-in-Laws old Tacoma failed inspection due to frame rust and he got a check from Toyota and bought a newer nicer Tacoma. You may fail your next inspection so I'd get politely aggressive and persistent right now regarding this frame. Unacceptable and scary.

As stated many times before, I wash/rinse it, per common sense, with any/all salt events and normal spring/summer/fall vehicle washings.

You are right, they did not appear overnight, corrosion takes time, but from what I can see this all happened from the INSIDE, not the outside. I deal with the marine industry and I junk more trailers than you count per year due to the frame rusting out, so I know how this all works.

Most frames rust out inside first as there is no easy way to remove the salt deposit inside vs a quick wash or even rain water on the outside. I have seen many frames look good from the outside, still clean galvanized coated, but when you tap with a hammer it goes right through like paper.

From what I saw on my frame I believe it was very similar as the outside in a couple sections.

Again, you seem to ignore my points about many other vehicles that I deal with daily that receive much less 'attention' are are still in great shape. There is a big elephant in the room and you are dodging it left and right.

This 4Runner, by far, has the worse frame anti corrosion ability of any vehicle I have seen.

Yes, any/all frames will rust out eventually if not taken care of, that is basic science. However, when you can compare a number of different frames all driven in the same environment, most older and receiving less washing, all all looking much better with no damage proves - without question - that the 4Runner frame is sub-par compared to other frames and requires significant attention vs the others to prevent this from happening.

I'm not dodging anything. I just think you're in denial. Like the guy whose lack of personal responsibility resulted in his filing a class-action lawsuit with some ambulance-chasing law firm over his rotted (through HIS own inaction) 4th gen.

You made assumptions about the condition of your 4Runner, because you washed the body and cleaned the interior. And will not accept that your own inaction played the major factor in the condition of your 4Runner.

I think it's clear you'd be happier in a Durango or Tahoe. Just an FYI, I've seen several rotted out examples of both. Not to mention their more prevalent mechanical issues.

At any rate, this is a waste of time to keep going around and around.

Good luck with the next vehicle.