Lexus ES300 Trans Fluid

[Greenie]

My wife's '94 ES300 is due for a transmission fluid change, however the dealer and a reputable Lexus repair shop only recommend changing out a small portion of the fluid ie: what is in the pan (approx four quarts) at a cost of $120. They also do not recommend removing the pan or cleaning the screen. The transmission has been serviced as per the Lexus schedule.
I am not sure if the pan has been removed in past service procedures. The service writer says the transmission holds fourteen quarts so that would mean ten quarts would substantially dilute the clean fluid.
The car has 189K on the clock and they say any drastic change of all the fluid would be risky. I suspect their fear of liability is overiding practicality or is there a real risk with a vehicle this age?
I would like to change it myself using the same procedure I used on my Tundra (with Mobil 1 synthetic or even Dexron II) but I am hesitant to make a major transfusion now that these Lexus shops do not recommend it.
This car has been trouble free with the exception of normal maintainance items towit: tires, battery, tune ups, timing belts and so on. I know nothing lasts forever but this car does not use oil and has no fluid leaks and the transmission shifts the same as the day we bought it.
Any suggestions?

[Greenie]

My apologies for duplicate posts, I was not logged in the first time.

[yspert]

flush the trans fluid with 14qts. remove the pan and clean the screen if you want. won't hurt a thing. on these vehicles, the "flush it and it fails"
trick does not apply. question: will clean fluid hurt my vehicle?
another question: will dirty/bad fluid hurt my vehicle? yspert

[lelandstanford]

If your ES300 has transmission service per schedule (every 30k?) then your next drain-and-fill should be at 210k.

[Greenie]

Can anyone tell me which transmission line is the return line? Went to the library today and searched Motor Manual and Chilton and found no detailed information regarding trans cooler hookup on this model. I don't think I'm ready to spend a couple of C notes on a factory manual no more than I would use it.

Figured it out myself. Located the two lines coming out of the transmission, removed left one as viewed from front of vehicle and turned the engine over and fluid came out of this fitting. This was the output line! I always pick the wrong one first. Re-attached left line and removed the right line (the one nearest to driver side of vehicle. Right line is the return line. From this point the procedure was the same as with the Tundra. Replaced the abominable pinch clamps with stainless screw drive type. Space is very restricted in this area and much of the time spent on this project was in removal of the pinch clamps. I might add that I did not drop the pan, I just replaced 14 quarts of fluid.