What's the word re rust on this generation of 4Runners? ...

I live in Western NY so I know me some rust.

Wondering if these are known for being good for rust, or bad, all things considered?

A friend told me he just checked out a used 2017 and it was pretty bad underneath, not completely destroyed but it definitely looked like more than just a little surface rust.

If I'm looking at 2015-2016 models up here is this something I really need to check out? Thanks!

Like any make and model, they can rust in a highly corrosive environment, if neglected. If you drive on lots of salt covered roads (like I do) then you need to be proactive in keeping it clean. Especially the undercarriage.

I'll wash my 4Runner as often as necessary throughout the winter. That could be several times per week. As I said, pay particular attention to the undercarriage.

If buying any used vehicle in the rust belt, yes, you need to check it for excessive rust.

There have been problems with excessive frame corrosion in the past. I don't know if Toyota has corrected this in more recent years. They have even replaced entire frames on a bunch of vehicles. Keep an eye on it and keep it clean. After winters here on Long Island NY I use a lawn sprinkler under it for about an hour to rinse it well. I need to look into getting some Fluid Film on mine just to be safe. I've have gotten under there and wire brushed any rust spots and sprayed them with Rustolieum.

I live in an area where they salt the roads heavily and vehicles rust accordingly, but it's nothing to what happens up in the Northeast. I never buy local vehicles and always shop out of state for rust free examples, which is what I would suggest for you. I would buy a rust free truck from a reputable dealer (out of state if you have to) and fluid film the undercarriage before winter. A vehicle purchase is a huge investment, buy quality on the front end.

8 years with my '12 in a northern Alberta city where they use calcium chloride spray on our roads nearly 7 months a year. Minimal surface rust on the frame welds, zero on the body, and lots on any of the poorly done powder coat on all the aftermarket accessories - bumpers, sliders, roof rack etc. Doesn't matter what brand, the powder coat sucks. I will say though that my Total Chaos upper and lower arms have stood up pretty well, but otherwise I'd avoid wasting money on PC.

For the truck itself though, I wash it at a minimum of every two weeks, and I specifically go to a drive through wash that had a good under body spray. I did not have any undercoat applied when I bought it.

5th gens have not had the same rust issues that plagued the 2nd gen tacomas, if that's what you're getting at, and I had read that after that debacle Toyota added additional anticorrosives to the mix for their frames to prevent the issues they were having.

Blue 4ever Runner said:

There have been problems with excessive frame corrosion in the past. I don't know if Toyota has corrected this in more recent years. They have even replaced entire frames on a bunch of vehicles. Keep an eye on it and keep it clean. After winters here on Long Island NY I use a lawn sprinkler under it for about an hour to rinse it well. I need to look into getting some Fluid Film on mine just to be safe. I've have gotten under there and wire brushed any rust spots and sprayed them with Rustolieum.

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The problem frames were on Tundra, Sequoia, and Tacoma which were improperly made by Dana Corp. Toyota won a 25 million judgement against Dana Corp, and replaced lots of affected frames.

The 4Runner having always been made in Japan, never received those improperly made frames.

BUT, like any steel frame, the protective coating form the factory can eventually fail, if sufficiently neglected in a highly corrosive environment.

I sold my 22 year old 3rd gen 4Runner last year when I bought the 5th gen. Despite driving every year on salt-encrusted roads in winter, it had no rust. But it took considerable effort to keep it that way. The payoff was a vehicle which I sold for way above high book.

I have had excessive corrosion on some fasteners. - small bolts that hold the skid plates on specifically. Other fasteners show zero corrosion at all. So at least one supplier of hardware is either not properly coating them, or they are incorrectly spec'd. My guess is the supplier cutting corners. But I don't know. This includes the screws and such on the plastic bumper covers.

My frame has surface rust, but minimal and as expected for its age. My body has shown zero sign of rust - even in places where paint has been scratched off. I think so far that the body and frame are not rust proof - but well coated.

I just this fall traded in my 2010 4Runner for a 2020. I bought the 2010 new, and it lived all 10 years in central New York. I did not have it undercoated or rust-proofed when new. I was at 155,000 miles when I traded it in. Overall, it still was in good shape, but with the 2020 updates I decides to upgrade, instead of waiting a few more years for a 6th gen.

Overall, it survived well, but this year is started to show it's age:
Body - over held up well, no rust, other than the tailgate. it started rusting from the inside out, and I was getting rusty water running out the drain holes after car washes. I had to replace the tailgate latching mechanism once due to corrosion. It still looked good from the outside, but I knew that wouldn't last much longer.

Underside - Frame was fine other than surface rust. The skid plate under the engine rotted out to swiss cheese and I had it replaced last year. The exhaust heat shields (mounted to the body, and to the headers/pipes/cats) all fell off in the past couple years. I started going through a lot of siezed brake calipers towards the end (avoid the aftermarket ones). The tow hitch was covered in rust but structurally fine. I had issues with the neutral safety switch on the transmission but it was frozen to the shaft and I could not get it off to replace it (oddly enough, after trying to get it off it worked fine 95% of the time until I traded it in).

In the winter I park in an un-heated garage at my home, and it sits outside when at work. I have a monthly automatic car wash subscription (delta sonic) which I use at least every 2 weeks or so in winter.

For my 2020, I had it undercoated and rustproofed when new. But, overall, after 10 years my 2010 held up pretty well with the upstate NY climate. Much better than my wife's Honda, which started rusting pretty bad about 5-6 years in.

speedmaster said:

I live in Western NY so I know me some rust.

Wondering if these are known for being good for rust, or bad, all things considered?

A friend told me he just checked out a used 2017 and it was pretty bad underneath, not completely destroyed but it definitely looked like more than just a little surface rust.

If I'm looking at 2015-2016 models up here is this something I really need to check out? Thanks!

Click to expand...

I bought my 2017 in 2019 from a dealer lease, which was an employee of said dealership and they claimed to have taken good care of it. This ND/MN area uses a lot of salt, and there was definitely some minor rust spots and any work i've had to do under there has been difficult. The shop that put my suspension on said the front shocks were very difficult to pull off. Bolts were rusted to fuk. I'm looking in to getting a professional clean and some sort of sealant sprayed on before the winter. Just don't know what I want to do. I think if you are careful to maintain it properly (just like anything) you'll be ok.

I recently acquired my wife's old 2014 4Runner (she got a new GX460 Lexus) as such I am going through and cleaning it and fixing little odds and ends. overall the frame was in good shape, no undercoating or maintenance done, though it was washed once a week or there about's during the year.

I went through the whole undercarriage recently and rust neutralized anything showing some rust (using the Loctite Rust neutralizer great stuff by the way). The welds were all getting some surface rust and as others have noted, anything with bare metal that would be exposed to road salt during highway driving was covered in surface rust. however nothing was deteriorated in any way. The worst part was the rear frame rail that the rear bumper sits on, it was by no means rotten, but it did have the most surface rust of any other area.

Overall the condition was significantly better than our old 2003 (just sold a couple months ago) granted the 2003 was much older, but you could tell that the newer 4Runner frames were much better in terms of rust proofing than the older models.

To answer the question of the Opening Poster, if you're looking at a 2015-16 and its covered in rust, it clearly means it was not washed at all during the winter. If ours is in great shape and is parked on the street in Boston and driven mostly on the highway in the winter visiting family then any on the market should be in similar condition especially if it had access to a garage.

I emailed Toyota corporate about a year ago and asked them if there was any type of anti corrosion coating applied to the frames when produced, their answer was no.

In the past and on this current truck I go over the underside welds with POR15, then apply Fluid Film with a gun to the internal and external frame and undercarriage.

I keep a small aerosol can of FF lying around during the winter to touch up the frame and will usually rinse off the underside at the local car wash bay during the salt/brine months.

I have been told trucks parked outside during the winter vs a garage fair better over the years in terms of corrosion/rust build up. I can not fit my truck in the garage so it lives under a canopy.

Rust, is lighter than carbon fibre.


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