Obviously from the title I am a noob 4wd owner. I had my 5th gen for 3 years now. I have driven in 4HI only 3 times I remember in 3 years. Icy hill, uphill climb on steep mountain, climbing on rocky hill on long trail are the three times I used it. Rest of the time it has been only driven in Rear wheel drive. Recently, while reading about sand driving(which I will do soon), I randomly came across a fact about how you should be driving in 4wd once a month at least 10 miles according to Toyota manual(which i seem to have skipped that part). So anyways, it sounds like it is good to drive 4wd that often to keep differentials lubed and not ruined. Obviously now that i know, I will do this going forward. But so far, what damage do you think has been done to my truck, since I only drove 4wd only 3 times in 3 years? Last time i used it was last week in the mountain, 4HI engaged and worked fine, no weird noise. Is it that bad, if I only used it once a year?

Can't think there would be any lasting damage... You should be fine.

On the 4th gen forum there is a monthly reminder thread that occasionally resurfaces about this. Although I think the 4th gens are an electric actuator and the 5th's a manual transfer case, which is why the 4th's can freeze up and not pop over to 4WD. Costly fix if that happens.

I don't have knowledge on 5th gen's.

It wouldn’t do any damage it just doesn’t get as well lubticated and the seals don’t get warm soft cuddly oil thrown on em as much as it should have.
You’re not the only person to rarely use 4wd and certainly not the last. A Toyota master tech told me what he does with his is just drive it down the highway once a month in 4wd. He said it was fine even when the pavement is dry as long as you aren’t turning of course but I didn’t like that still. So what I personally do is when I’m on interstate and it’s a rainy crappy day like today I throw it in 4wd for a while. It comes out to about once a month that I do it so it works out well.
Remember don’t ever drive in 4wd on dry pavement and certainly don’t make turns with it engaged on pavement cause it will cause the system to bind and you’ll break some gear teeth or something else. Look in the FAQs at the top of the 5th gen forum and in there is the topic of 4wd dos and don’ts and what ifs. Very helpful newb info

Read this

Did You Break 4WD?

On the other hand it would have been nice if Toyota didn't try to save a dime or two by removing the AWD feature that I had on my 2001. Didn't have to worry about making a turn when you were in 4WD. They apparently decided only the Limited needed that feature on my 2016

You don’t need to engage it every month with either the electronic actuator or manual lever. Maybe every few months, pop it into 4hi and 4low just to make sure it engages properly.

Dude! You're probably fine... but you're in one of the best off-road states! Even just going out for a drive to the west desert or something and hit some dirt, and you can engage it. Try some of the forest service roads and you're really gonna love your 4R Nothing too serious, but I use my 4HI going along dirt or up into the hills, and then 4LO to come back down some of the rockier and rougher roads. I've even used my crawl control more than a few times that way. You want to appreciate what you bought, just get a minute or two and get off pavement. Salt Lake City? Hit Parley's, take the Jeremy Ranch exit and head north across some dirt through Mormon Flats. Or, head out on I-80 past Tooele and Grantsville and explore Stansbury Island, Skull Valley. If you really want a day, hit the Pony Express Trail and take it west to the Nevada border, hang a right, and grab dinner in Wendover.

There's so many spots close by... I know you can be real busy, but it won't take you more than an afternoon to exercise your 4WD and lovelovelove your 4Runner!

My 4th gen wouldn't go into 4lo, no matter what I did. I bought it used and I never checked to see if it would go in 4lo when I was buying/inspecting it.

4x4 PSA: Use it or lose it monthly reminder

I go through and put it in 4hi, 4lo, turn on ATRAC, turn off traction control, lock the diff, etc around once a month to cycle everything and prevent what happened to my 4th gen. Whenever I am driving on a gravel road I also throw it in 4hi as well.

Nice avatar photo, probably not wife approved, but still funny.

You can drive it in 4Lo on dry pavement if you don't turn the wheel. Find a straight section of road. You can even make a 180 degree turn if you go very slow. Listen for wheel skidding when you do. To shift, come to a stop, put the gear shifter into neutral and slowly shift into 4Lo.

You can drive in 4Hi anytime. Only put it into 4Hi when you're driving 50 mph or less. After that you can speed up a bit. Read the manual for more info on shifting. Turning sharply in 4Lo will also cause wheel binding, unless you're on loose dirt, snow or very wet roads.

You can also try 4Lo on very wet, smooth concrete pavement. On that kind of slick surface you can probably turn the wheel.

I like to drive it in 4Lo for a mile or so just before changing out the front differential and transfer case fluid. It stirs up the dirt so it can drain out of the case with the oil.

That’s not from Toyota trying to save a dime or two

Zero damage in my experience.

I've owned three 4runners, an 87, a 99 and a 2011, the 87 I had for 12 years. The 99 still own and as well as the 2011.

I never use 4wd monthly in any of them, maybe 3-4 times a year at best.

I've had zero issues with any of them related to the 4wd, transfer case, seals, levers, bearings, leaks, etc, etc, etc.

What about the limiteds? My 2017 ltd has full time 4wd and I have never tried 4low and 4hi since I don't really need them for my 99% of city drivings. Should I find some trails to engage them every once in a while? Thank you!

So with all of the people out there buying used 4x4 4runners... there is a pretty good chance the car they buy, might only been used in actual off road a few times.. are you saying the gears can already be damaged?

I brought this up to a co-worker of mine whom own a '16 Tacoma TRD 4x4, he said he only use it every 8 months or so when they go to the mountains in the winter time, all other times it's in 2Hi. He did not know about the once a month regiment.

No. That's not what we are saying.

What we are saying is that if you don't put it in 4Hi and 4Lo every once in a while there is a CHANCE that eventually you go to put it in either of those and the 4wd light just flashes and it never engages (happened on my 4th gen)

As long as it is going into 4h/4l then all is well! The point it to do it every once in a while to cycle the electronic solenoid.

Edit: Okay the post I was replying to above me is now gone?