ATF Drain vs. Flush at 300k miles with Unknown Service History...

Hey folks, long time lurker first time poster...

I recently purchased a cheap high mileage (306k) 2003 v6 that has a laundry list of minor issues that im slowly knocking out and ZERO service history in the last 100k+ miles (since the original owner parted with it).

Currently the engine and trans are operating fine, maybe the occasional clunk/hard shift under load/into reverse but for the most part everything works smoothly.

That said, I am trying to establish a new service interval baseline for at least the oil and ATF, as both are looking far from fresh. I was all set to flush and refill the ATF, maybe even drop/clean the pan and replace the filter (following Timmy the Toolman's excellent DIY videos) but then I got to reading a few threads here about how flushing higher mileage transmissions can actually do more harm than good and that a drain-and-fill over the course of a year or so was a better course of action.

Ok, fair enough.

But all trucks mentioned in said threads had 250k or less on the clock...same rules still apply to 300k with no service records and black ATF on the stick?

Thanks in advance for humoring me on this one...I know its been discussed many times over I just dont want to make an avoidable mistake, trying to prolong the life of the truck as much as I can!

 

You would likely do more harm than good flushing, if the fluid is really black and stinky it may not even be a good idea to drain and fill IMO. @gearcruncher could probably give you better advice, he has quite a few write ups on here about all the transmissions in the Tacoma trucks.

 

Agreed with above. Often times the friction material wears off and is suspended in the fluid. The fluid is the only thing holding it there so when you flush it out, you'll notice more shift slippage afterward. The only real solution to that would be a rebuild to replace those worn materials.

 

Thanks for the quick 2c...I didnt do a sniff test yet but the fluid is definitely not red, ill say that much.

So what ARE you supposed to do in my case, if the fluid is toast?
Just wait for it to implode and then replace the entire trans? Seems kinda ridiculous.

 

If the trans is already on it's way out sometimes new fluid will finish it off, like I said Gearcruncher can give you better guidance than I can, he is the resident transmission guy on here.

 

Nothing to worry about, horror stories of flushes damaging high mile trannies are because high mile trannies are tired and old already.

Drop the pan and clean magnets/screen. Don't stress about the myths.

 

Zero trans service in 100k?

You could change the fluid, and if it works, great. you can keep running the truck

You could not change the fluid, and if it works, great. you can keep running the truck.

Or.

You can not change the fluid, and have to do a rebuild either with or without a fluid change. The risk is up to you. If the risk of changing the fluid is the same opportunity cost as having to get a new transmission build, I'd just change the fluid and roll the dice. Math says you're better off playing it that way.

 

You have the 4 speed auto with a dipstick . What does the fluid look like when you perform a level check using a white rag ?

The proper way to service a transmission is by removing the transmission pan .
To flush or not to flush is determined by the sediment in the pan and filter .
Order a pan gasket and a filter and 11 quarts of fluid .
If the pan is clean and the fluid is reddish brown , flush the remaining fluid .
If the pan has sediment , the magnets are covered with particulates and the filter is dirty , just add new fluid to the pan .
More reading here

https://www.tacomaworld.com/threads...sions-write-up-your-4-speed-automatic.325531/

 

Thanks for responding, working my way through your thread you linked right now...

I wanted to clarify my course of action, just in case it doesnt qualify as a "flush" in the traditional sense of the word. Sounds like most shop flushes employ some sort of machine to force fluid through the system? I could definitely understand how something like that might churn up some undesirables.

This is my first time doing this kind of service so I apologize in advance if im missing something...

1 - Drain/Drop pan
2 - Clean pan/magnets and swap filter
3 - Remount/seal pan
4 - Replace drained fluid
5 - "Flush" via Timmy the Toolman's method
6 - Hook up trans cooler then top off fluid as needed

No machines will be used to cycle the fluid (except the truck).
Maybe that doesnt matter but im hoping it might?

 

between number 3 and number 4 you need a 3.5 ....Determine if there are too many sediments and particulates to flush . I suggest popping a picture and post it up .
If you leave 3.5 out and you flush your transmission , you could be in for grief . In a flushing scenario ,11 quarts of brand new transmission fluid with an extremely high detergent concentration is too much for the transmission all at once .
If the trans pan is dirty , magnets and filter are dirty , clean the pan , replace the filter and add fluid to the pan ...do not flush .
This is why we remove the pan first . You need to know the contamination level .

 

Right, makes perfect sense, thank you for taking the time to respond.
Ill be sure to post a photo of the pan and fluid color here for review before moving forward.

I am hoping by some miracle its far cleaner than 100k+ of (suspected) neglect might leave it.
The truck drives/shifts fine right now, I wouldnt describe it as feeling "on its way out" so I'm just trying to do whatever I can to keep it that way (or improve it).

 

Finally got around to dropping the pan...breaking that FIPG seal was a PITA without the special little tool but i finally got it.
Drained almost exactly 5L of fluid from the pan and return line. Havent removed the filter yet (ran out of daylight).

Overall, im pretty happy with what Im seeing.
- No non-ferrous metal flakes of any kind in the fluid/pan.
- Magnets have a sludge on em, which I was expecting.
- Fluid is a brown with a slight reddish tint to it.

Im leaning towards replacing the filter and refilling with new fluid, then driving it and see how things feel.
If all is well, revisit the flush option this summer when I dont have to roll around on the ice/snow/dirt in 30* weather (id KILL for a garage right now...hell, id settle for pavement! ha).

Here are some pics of the situation (@gearcruncher), thanks in advance for any comments/suggestions!

 

Well thats great news . Thanks for posting pics . Surprisingly clean for unknown mileage
I think you will be fine cleaning up the filter and adding fresh fluid to the pan .
I hate the formed in place gaskets . such a pain .
This is why i go with the cheap cork gasket . Easier to clean the next time you have the pan off .
I like your idea of flushing this summer .

 

I bought a Wix filter locally which came with a new (rubber) gasket, think the rubber will be ok? (vs cork or FIPG)
Personally, I like the idea of rubber over cork...feels like less of a chance some little piece will break off and fall into the pan at some point?
Maybe a moot point considering the filter gaskets are made of cork...

Comparing filters (Toyota vs Wix) I see very little difference between the filter mesh and gasket materials and the OEM filter actually appears to be quite clean...
For half the price I figured it was worth trying it out as I've had good experiences with Wix oil filters in the past.

There is a chance that the fluid was changed at some point I just have no service records past 200k (via the toyota owners website/dealer service log)...which was 106k miles ago at this point.

 

If I had to guess , I would say your fluid was changed judging by the color of the fipg on your pan . I believe Toyota uses a grey fipg from factory .
a rubber gasket is fine as long as you dont add fipg along with the rubber gasket .
Some guys place a bead of fipg on the rubber or cork for that matter in an effort to get a better seal . The bead of fipg forces the rubber to squish and you end up with leaks .