2007 Tacoma 254,000 miles

I don’t know if the transmission fluid has ever been changed. I’ve been told it’s is sealed unit. It runs and shifts perfectly. It’s an automatic. Thanks.

 

If it’s running and shifting perfectly leave it alone. If you decide to service it. Here’s the whole shebangabang(https://www.tacomaworld.com/threads/how-to-drain-refill-automatic-transmission.63851/). I only use Toyota ATF AWS. Cheers!

 

I seriously doubt you will have any issues doing a drain and fill.
You could even do a pan drop, magnet clean, and replace the filter and I doubt you’ll have any issues.

What I wouldn’t do, is flush.
Not unless it’s done correctly.

 

It will shift perfectly until it doesn't. All fluids accumulate contaminates. Filthy fluid may or may not cause your transmission to fail. The purpose of changing out the fluid is to eliminate the fluid as a possible failure point. It is relatively easy and affordable to do for a diy’er. BTW Toyota/Lexus states to flush the ATF every 60K if the vehicle meets the special operating conditions - towing, off-roading, long idling (commercial use), etc …

 

Do you have any specific questions?

 

My theory on high mileage trans that have never been serviced is that the fluid contains the friction material in suspension (from wear on the friction discs), and if you start to change out the fluid, slippage will occur.

So I agree on not doing a flush, but I would also say that a 4qt drain+fill could also put things in jeopardy? Hard to say for sure.

But 250k miles on a transmission = rebuild time, regardless.

 

should have started servicing is 154k miles ago

 

I did a drain and fill on my 09 sport at 100k and again at 200k. At 235k now and no issues. Knock on wood.

No off road, towed 1000 lbs 150 miles weekly in summer for 9 years. Now 4000 lbs 40 miles 2x per year. And occasionally a utility trailer under 2000 lbs locally. 14 years on 285 tires.

 

that's how it should be done. unless you tow then its every 60k

 

If it's made it this long and it's not slipping or having issues then it's probably best to leave it alone. Every mechanic I know says that after that many miles the friction material in the trans fluid is most likely the only thing still allowing it to function properly. When my trans started shuttering really bad earlier this year and needed a rebuild the transmission guy said the same thing. At that mileage it's best to not mess with it.

If it ain't broke dont fix it.

 

At a minimum, I would replace the ATF filter and clean the pan and magnets. If the pan has the usual slimy black gunk and no metallic pieces, you can proceed with a drain/refill or flush.

 

X2 - I've always heard drain and fill -NEVER flush a old trans - problem is the flush might stir up some crap and clog passages then that's it for the trans.

 

If don’t right, a flush won’t cause problems.
If it does, there was already a problem.

Again the key is to do it right.

I’d still stick with a drain and fill. Because that’s what I feel more comfortable doing myself.

 

You could also put a Magnafine filter on the return line from the cooler to the pan to filter out any junk in the fluid.

 

2007 with 240k miles here... I religiously change my transmission fluid, filter and clean my magnets every 75k or so...

Did my first transmission filter swap, magnet clean and fluid swap @ 75k miles

2nd filter swap, magnet clean and fluid swap @ 150k miles

I just did my 3rd filter swap, magnet clean and fluid swap few months ago around 230k miles.

I installed an aftermarket cooler as well to prolong the transmission life and prevent atf from getting too hot in the Texas heat. I was seeing transmission temps of 210* on average without the cooler and 184* consistently with it.

 

On a high mileage transmission, I would not introduce anything new in my transmission lines that restricts flow. If you already have one, I’m not saying to remove it.