ATF fluid changes ARE Required.

Hello, This is my first post and after lots of research on the forums about this subject, I think we need to start a new thread. There is too much diverse and hard to find information on this simple subject so let's review:
The Prius transmission is not a typical 'automatic transmission' with torque converter,clutches, valves and a lot of gears.
It is not a typical 'CVT' with a metal V-belt and varying pulleys.

It is simply a Planetary Gearbox with two electric motors in it;
one motor controlling the the planet gears for ratio changes
and one motor connected only the the drive output for electric only moving and reversing.
That's right, there is not even a reverse gear set. This is incredibly simple !

Unfortunately there is no mention of changing the transmission fluid in the manual, only checking the level at 100k mi.

I'm a Noob. I purchased my '10, IV, Solar Sun Roof, (over $30k on the window sticker!) in November with 108k mi from the dealer that sold it originally.
At 112k mi I changed the ATF and sent in a sample for oil analysis.

The ATF change is incredibly simple. If you can change your engine oil (buy the 64mm filter tool),
you can change the ATF fluid. While you're under the car doing the engine oil, look to the left by the axle shaft. There are the drain and fill plugs. Buy one of those transmission fluid funnels with the 2' foot clear tubing, go to the hardware store and buy 3' of the clear tubing that fits tightly inside the funnel's tubing and you have the only tool needed, besides the 10mm allen socket, long extension and ratchet.

Attached is a story of 5 oil analyses, two from my car and one from a buddy's GenII with 250k mi.
The first analysis scared me so bad I did a second ATF change 420 mi later and I show that analysis, also. All of these are Toyota ATF-WS.

I used Mobil 1 ATF this time.

IT'S JUST GEARBOX. That's all it is and it needs routine oil changes because there in no oil filter in this gearbox and Toyota didn't even give it a magnetic drain plug. Gen 2's have a magnetic drain plug.
That, and the lack of scheduled maintenance, IMO, Toyota dropped the ball on this.

I also added a 'super' magnet to the drain plug.
Attached is a picture of my improved drain plug.

2-17-14_UPDATE: I added a marked up report with 4 different analyses and a current report from my buddy's new Gen 3 with the ATF changed at 104k miles.
His results were similar to my first. The fluid was "too dark to do the particle count.

 

I put a small smudge of sealant on the bolt before placing the magnet then wiped it smooth.
This is mainly to assist in cleaning it next time; no chance of the ferrous fuzz getting between the two surfaces.
These magnets are strong! There is no chance of it coming off accidentally.
They can be found in "Science Supply" stores that cater to kids and their projects. Hobby shops may have them also.

 

Other Toyota cars have ATF changes scheduled at 30k miles. They probably should have done the same with the Prius.
I suspect when it came time to spec a fluid for the Prius they went with what they had.
Other automatics have wires and valves and clutches and such. The Prius only has wires in its gearbox.
Any light viscosity lubricant could probably be used. A light MTF would work fine.

The deal with some lubricant manufacturers saying their ATF is not for a CVT is because "Real CVT" transmissions use that metal V-Belt and varying pulleys and those requires certain 'friction modifiers' in the recipe.
The Prius is not that kind of gearbox.

Let's not argue on the flavor of lubes.

Just change it. Immediately if it is a used >30k mileage car.

This is SO important I think it should be near the top of FAQ's for buying a used and maintaining new Prius.

And if you're a Nerd like me spend the extra $15 and send off a sample to get an idea of how the car was maintained.
And stick a magnet on the drain plug for good luck!

 

Is the ATF fluid Toyota puts in the highest-end Lexus and the lowest-end Echo distinctly unique and the only fluid that should be used in the simple Prius transmission?

Let's not argue about the Flavor of Lubes.

Some people still argue that synthetic engine oil is an 'experiment'.

I plan on being with this car for the long haul. That's why I only use what 'I' think are the finest available lubricants.
Only time will tell, correct?
Until then it's all just opinions.

Side Note: Before my second drain and fill, after I knew what had been slouching around in there, I was tempted to do a top speed run to sling off any ferrous specs still hanging on to the MG's rotors/magnets. I wasn't feeling lucky that morning, so I didn't do that step. Is this a consideration? And, what is a typical GenIII top end on a straight and level road?

 

Roger, and Wilco.

This was not advice.

Just an opinion.

Just as you are giving.

That is what Forums are mostly about, right?

Sorry if I sounded like I was giving advice.