Rust!!.. What rust??
P.S. this is my GX when I bought it..I rust proof it every year or two since..
The GX you're posting is called "Rust Free" up here.. Go for it..

 

Here are a couple pics of my 2017 GX 460 with about 34k miles. The part of the frame where the suspension part (pardon my ignorance) goes into is flaking off paint. I put my hand inside the hole and I can feel metal or paint flaking off as well, particularly down that center seam. I struck the part a few times with a broom handle and it seems to be solid. But since this holds a suspension piece, do I need to be concerned that this part of the frame may fail soon? Does the scaling (or paint flaking) on the inside indicate that this part of the frame needs to be fixed before Fluid Filming? And of course, I'm going to a shop to Fluid Film soon thanks to this thread. Appreciate your thoughts in advance.

 

I wouldn't be worried about that area. It's relatively open and water will drain. I would deff try to get all of the loose flakes or rust out before fluid filming.

The area that's more important are the enclosed areas of the frame near the front, such as in the pic below (gx470).

Below are pics from my 470. It had the most rust in the front part of the frame rails where the exhaust manifold comes down into the cats. I put a steel wire connected a drill going through a thin plastic hose. The other end was connected to a small chain or something to agitate the rust. Then I got some powerful magnets and duct taped that to a wire coat hanger and fishes it through all the holes. That got a lot of rust out. Then I used a shop vac duct taped to a small hose to suck out the rest. It got most of the large pieces out. Lot of work. The pile of rust u see is all that was removed.

Then I used CRC for external and as far as I could get internally. It's superior to fluid film in how long it lasts, but it doesn't creep as well. After CRC hardened I used fluid film with the straw to get into the deeper parts of the frame that the CRC couldn't get to. Make sure your don't shoot the straw into the frame.

 

Not an integrity concern yet but you caught it on time to start rust proofing. Left untreated it will develop a big problem in 5 years or so.

 

Thanks @JohnnySack, that's reassuring. Appreciate all the tips. Ingenious way to get at that frame rail. Will definitely keep an eye on that.

 

Thanks @JZZFZZ, appreciate that and good to hear. I'll definitely get the Fluid Film done asap and will keep an eye on it.

 

Lee, that rust doesn’t look too bad. I’d suggest getting under there with a wire brush and drill or grinder with a wire cup and remove as much loose paint and rust. Then paint everything you can before having fluid film applied.

 

Fyi:
CRC:

Project Farm comparison of Fluid Film, CRC, paint, etc

 

Thanks @Wmb67 ! Will do - really appreciate the input as well.

 

Project Farm is a fantastic resource!!

 

Fluid Film is honestly incredible stuff, I buy like 6 cans every late summer / early fall and hose down the whole underside of both our 4Runner and GX. the GX (while only 4 years old) I have been coating it since new and it looks virtually brand new from the underside. our 4Runner I only started coating after we had it for about 5 years (5 winters..) So I spent some time getting rid of some of the surface rust that was visible, but after coating it now for about 3-4 years i can tell that no rust has developed further since what was there when I started coating it.

Highly recommended, though I will say if you have a lift and can really get under the rig you can do a way better job than I can with likely even better results, i crawl under our 4Runner and GX on the street.

 

Hello!
Lookin at a used 2020 GX460 premium.
$43k
From eastern WA.
37k miles.
Regularly maintained at Lexus.
Does it look like the rear end has/had a leak?
A bit of surface rust here and there.
Frame has a layer of grime.
Thoughts?

 

Besides the oil splatter looks very good. Regular Fluid Film treatment and that will last as long as you want it to.

 

looks almost perfect to me. Has to be from non rust belt areas.

 

Make sure there is oil in the differential.