It seems to me that people are bragging on high mileage tranny fluid like it's a good thing. Which it's not. This isn't like bragging on how well your high mileage T4R is still running. This is bragging about neglecting basic maintenance.
As said before, there's no such thing as 'lifetime' tranny fluid. It's a marketing schpiel. It might get you 100k, but you want to at least do a drain and fill pretty regularly.
Funny the places experience leads. One year ago I would have agreed with this statement completely and still can not fault it on concept. Regular and proper maintance on is a good thing. However, below is a summary of my experience with my 04 SE V8. You may find my experience interesting.
I bought the vehicle in 2014 from the second owner with about 155k in excellent condition. I believe it was a freeway commuter most all it's life. It was a divorce sale car with a 60k (other than quicky-lubie type place oil changes) gap in service records.
Howver, the vehicle has been in harsh Colorado conditions for many years. From the hitch condition and the fact that the trailer brake pig-tail was in the glove box in orginal unopened condition it was a reasonable assumption it never towed much if anything. I drag a 3k trailer in the summer months up and down passes at altitudes ranging from about 7k to 11k feet. Suficant to challenge the condition and maintenance of an automatic transmission.
I was leary of touching the fluid at such high mileage. After doing as much research as I could tolerate (both here and the Tacoma and Tundra sites) I concluded two things. I should do something soon (which I new but did not want to admit). The other was that Toyota Motor Company seemed to recommend multiple drains and fills rather than any type of flush (there is a factory procedure for drain and fill I've yet to come across one for a flush).
A note here. I was not optimistic at this point. But told myself the vehicle's transmission functioned near flawlessly and if I would like any chance to keep it that way I'd better do something soon. My concern over touching an untouched tranny at such "high mileage" even lead me to price a factory rebuilt unit. Most Toyota parts department had them at a reduced price of under 3k at the time. I figured that and about 30+ hours was my worst case situation.
I was careful and kept everything as clean as possible and things worked out well. If one follows proceedure and avoids obvious pitfalls and shortcuts it should go well.
As far as checking the fluid level my feeling is if you can't follow the instructions for the factory suggested meathod and entering your vehicle's software into the temperature check mode you most likely should not open the hood let alone get near any piece of machinery with a wrench let alone a vehicle that is going to be on public highways. There is a lot of fear mongering here not completely unfounded. I think when you start shoving jumper wires across computer terminals you best be certain they be the correct terminals.
Back to the condition of my fluid.
I know if was the orginal fluid, or at least not changed since about 2006, to the fact that it had the "purple tinge" to it. My research here indicates Toyota changed the dye used in WS fluid along with a slight re formulation sometime in 2006.
It did not pull the pan as there was virtually no residual or sludge that drained with the fluid. Zero signs of any burning, overheating, no specs or particles of anything. I repeat none.
I took four drain and fills to get the fluid to an appearance of apparent clearity to please me enough to call it enough. I used the droplets onto white paper here. I needed 14 or fifteen quarts to complete the job as recall. 2 new or spotless transfer pumps on hand is advised
My take is that if one has basic shop skills, follows carefully correct proceedure, realizizes they are working in compromised at best conditions (rather than a properly equipped shop) and take extra time required by the restrictions of this comprise then you should have no dire issues. I'm assuming one has the mental capacity and good enough judgement to read through the many post on the subject and distinguish between information and mis-information. And be aware of why proper proceedure is critical and and methods employing questionable shortcuts or "iffy" thinking while they might perhaps well get you by in the world of bravado and rhetoric they will in the long run at one point or another lead to premature failure when applied to the hard reality of machinery
maintenance and repair.
