I did this on a 160k mile 98 blazer and the trans crapped out. Is that going to happen on my 317k mile truck? What should I know specific to the 4runner when changing trans fluid? This is for the auto

The trans crapped out because it was already on its way out, that and it’s a 98 blazer. A drain and fill with new filter isn’t going to hurt anything

It's not going to hurt to several drain and fills to get some lubercating fluid back in the system. Then drop the pan clean the magnets and replace the metal filter.

I personally exchange all the fluid and once. However, lots of folks perfer the drain and fill method.

The 3rd gens hold about 3 gallons of transmission fluid. The drain abs fill is close to a gallon of fluid. So it needs done several times like 3 to 5 times to get most of the old fluid out. You never get it all out unless you exchange the fluid out. But 5 spill and fills probably get 95% of the old fluid out..


Anything is better then doing nothing. As most likely the magnets are really covered and your transmission filter is probably fairly heavily clogged at 314k if nothing was ever done.

Now if your having any transmissions issues at all this isn't going to fix it. Mostly people wait until they realize something is wrong then change fluid.

Then say the new fluid killed it when in reality the transmission damage was already done.



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If Toyota didn't call it """lifetime fluid""", then they 100% expected you to change it at regular service intervals.
This whole myth comes from people thinking perhaps after many years the fluid becomes so laden with fine shavings and clutch pack material that it becomes so thickened/heavier and helps keep the trans from slipping and assists in engaging gears... If you know practically anything about a transmission it shouldn't take you longer than a few seconds to see why this is is loopy.
There's a reason they don't huck a bunch of shit like graphite dust or steel glitter into ATF before selling it, and a reason why transmissions have filters.
I did a full flush at 290k and the only difference I noticed was firmer, shorter shifts. Seems pretty good in my book

Great to know, thanks! Trans is running strong but sometimes it wont downshift when cold. Very likely it needs a flush.

The transmission on my third gen. with 280,000 miles was slow to shift gears, especially when the engine was cold. I had the transmission flushed and filled. I now have 286,000 miles and it shifts perfect. Very glad I had it done.

One of the experts can correct me if I'm wrong, but I seem to remember reading that the ECU puts the shift point at higher RPMs until the trans fluid has warmed up. So it feels like the trans is reluctant to shift when in reality it's programed that way. I imagine a full fluid exchange would lead to faster shifts across the board, both when cold and hot, so you would notice a difference on cold mornings.

Cold start in the morning it holds 2nd longer.

But now Toyota does claim "Lifetime" fluid for their sealed transmissions, which is utter BS. No fluid lasts forever. What they really mean is whenever your transmission craps out because you didn't take care of it by doing regular fluid exchanges, that was its lifetime.

I don't agree with you that the theory you mentioned is "Loopy". It actually makes sense that worn clutches are relying on the thicker dirty fluid with suspended friction material to not slip. Another theory is sludge deposits have built up inside the transmission because of the lack of maintenance. When you introduce new fluid that has great detergent qualities, it works on the sludge deposits and breaks particles free. Those particles can get lodged into small fluid passageways like in the valve body and basically give your transmission a thrombolytic stroke.

The filters on these transmissions are really a fine mesh strainer. They only grab the bigger chunks.

Who knows, maybe it is all wive's tales but there's been enough people who have reported issues after doing a fluid exchange on a high mileage abused auto transmission that there seems to be some credence to the concern. There's also lots of shops that advice customers against doing a flush.

The key is to regularly service the transmission fluid to avoid excessive wear. ATF at best can last 100k miles before it's totally broken down. How these transmissions continue to shift with some of the abuse they've been put through is amazing.

If it were me, I wouldn't touch that fluid, because the damage is already done. That transmission has been on borrowed time for eons.

I did a flush at 215, unknown if done before. I did the flush doing it the way timmy (MBTM...above) does in his video's. Dropped pan and cleaned all. I also added a magnafine filter. They have a magnet in them as well as a finer filter.
On previous 4runners after doing a flush, I then just do a drain and fill about every 3rd engine oil change. I change the magnifne filters every 15k although they say good for 30k.
I have always switched them to synthetic.

Yes cold morning can effect shifting....but I have days of minus 40

In all my 4runners, past and present, i have done flushes and have never had an issue. Knock on wood

All of mine have had exchanges of fluid with over 200K miles on the transmissions. Some could have been fluid changed before but I have no way of knowing as they are used. I think is good practice every 100K miles to exchange the filter and the fluid. Clean the pan magnets. Adding line magnet filters is not a bad idea.

I prescribe to the theory that I want to know if a transmission is going to fail if possible before it does and leaves me stranded some place.

If your fluid is black and smells burnt. Nothing will save it. Old fluid is sand blasting your transmission with all the debris in it as all lubricating properties would be gone out of the fluid all particles smaller then the filter screen are circulating around.

This is why I suggested the spill and fill method as your only changing a gallon at a time. As getting some lubricating properties back in the fluid would be a good thing. Thus preventing further damage.

As what mostly happens is the fluid gets so contaminated that it loses all the good properties and then Clogs your screen filter with sludge thus reducing the volume of fluid the pump is able to circulate. The continued restricted fluid will raise the transmission temperature and start breaking down the fluid faster. This continues until the clutches and other components start to fail mostly scattering the clutches and other sensitive components all through the transmission.

However, Folks can do as they wish as its their choice and their rigs. :-)

I used to lose Camry transmissions at around 200K or so miles by doing nothing. Then I started to look into what what going on as most of my autos that failed blew their clutches. Once I started exchanging fluid around 100K with the filter changes. My transmissions life were being extended. They actually rotted to nothing or junk before transmissions failed.

There isn't any lifetime fluid in any transmissions. The vehicle mfg want transmission and engines to fail so you go buy a new vehicles. This is why even in the newer so called sealed transmissions its best to exchange your fluids and clean the magnets with a replacement of a screen filter every 100K miles or so. (If they have a screen filter)

Me and Timmy the tool man are going to have a sword fight with our wieners, if I win you drain and refill the fluid, if Timmy wins you shoot your transmission with a rocket launcher and buy a new reman from Toyota

Watch the cock fit seen in the movie “Skin Deep”. It’s what I have in mind.


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Good grief. Where do you come up with with stuff ...:/ This forum is rated G for general audiences

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I like your sense of humor, but I'm not going to sword fight with you. I would like to see a transmission hit with a rocket though.