What's an argument without a contrary point of view?
I have a 200 Series, diesel with a six speed auto. According to Toyota the transmission doesn't need servicing, and the transmission fluid is meant to last the life of the vehicle.
Several posts on LCOOL caused me to arrange a transmission flush recently, with a requirement to keep a sample of the old fluid for me. The transmission takes about 11 litres, 9.5 litres were used in the flush, as without breaking down the box, it's not possible to get all the fluid out.
After 53000 km, about half towing a 2.2 tonne camper, my transmission fluid was blacky/burgundy, as opposed to the usual red-cordial colour of
fresh transmission fluid. The flush cost me $215 and I'll be getting it done regularly, either 20K or 30K from now on.