ATF fluid changes ARE Required.

There are techs, and certified mechanics. Guess which one does the oil changes at the dealership, hence all the over/underfilled oil levels, over torqued oil filter housings, etc.

 

The one's that do the tire rotations and oil/filter changes in the Express Lane at Dealerships are non-licensed, unskilled labor...just like most of the car owners here...as it pertains.

 

He was referring to the "tech" as the person updating the inverter software. Not much "mechanical" there, I guess. I have the feeling he calls them all "techs" though.

 

Yep, probably does. Or, he calls them that to "dumb it down" for the customers, so we don't get too confused with technospeak.

 

I was reading an article on how to write a resume. One caveat: don't describe yourself using the job title you're assigned by your current company. Chances are no one outside of the company will have a clue what you're talking about. I was with my last company about four years when an edict came down: we all had to make an email signature which included our "official" job description, title, whatever.

That took some doing, lol. I'd hazard about 50% of the staff never did complete that task. I was lucky to get clued in as where that info resided, found my title, whatever the hell it was, can't recall now. Think it said "special" and "technical" and a few other words.

Have no idea what it meant; thought I was a "checker" up to then.

 

Grease monkey is the proper word. I use to change all the fluids at 2K on a new car/as in all. Don't do that anymore as it does not seem to have a proper cost benefit analysis. The Prius is not a 55 Chevy Bel Air convertible.

 

I would do my own oil changes, even if I just broke even. We don't have the "free" maintenance for the first while up here, makes the decision simpler.

I do not know if it's just me, but I found once you've done your own, bringing it in for an oil change is kinda soul destroying. Listening to service writers tell people they're gonna get the 100 point check up, joining the walking dead in the waiting lounge, looking at their smart phones. Arghhh.

 

I can assure you if there's any leakage current in the trans the Inverter will sense it as a ground fault and throw a ground fault nag. Leakage current will not make it less efficient it will make it stop running. There is no room for "minor" leakage current. And leakage current increased by high metal content in the oil is ludicrous. That supposes a Prius with 300,000 miles with the trans fluid never changed with the oil black with GL4 and metal wear (highly conductive) would have very high current leakage. Lot of them on the road. All driving around with hi voltage leaking. Quite a trick.

The Prius has highly sealed stator coils to prevent what your claiming from happening. Very tough coating. Even a tiny pin hole in the stator wire insulation will result in a pretty good flashover blowout almost immediately at the voltage and current the mg's see. There is no tolerance for even tiny leakage in a 3 phase system.

I see all your quotes come directly from the SAE article. I especially like how they say at the end that this special fluid has been developed.
Thats nice. What is it? Where is it? Sure ain't WS which is basically non synthetic trans fluid used in a very large platform of non hybrid toyota cars.

I can only imagine if this car has what you suggest is a voltage leaking problem with dirty fluid how it would be perceived in the market. And it has to have this special fluid to stop the sparks. Pretty sure I wouldn't own one and neither would you and neither would anyone else in this country. The Prius would never have made it. And why should it? There transmissions leak high voltage. The red states would have a field day. Instead it has lifetime trans fluid. Move along nothing to see here.

Btw, I'm on my 8+ years and 100,000 miles on aftermarket 100% synthetic trans fluid on my new to me G2. Still waiting for sparks.

Oh and btw, WS turns dark like any other trans fluid. From mostly metal wear not whats in the fluid. I moved over to my other fluid at 1,000 miles from new. It was getting pretty dark. Every successive fluid change at 30K has been much much cleaner because less metal wear due to break in. Last one at 75K miles was pristene after 30K wear on it. Nothing to do with dispersants. Everyone who changes there fluid reports the same thing. Older it gets after a few changes the less metal wear in the fluid.

 

I thought about this for a while and came to the conclusion why would Toyota go through the trouble of exposing the windings to trans fluid.
It would have to be a very tough coating and the only thing that would hurt the windings coating would be if the fluid became very acidic.
The trans fluid becomes conductive pretty quickly and would quickly foul the stator assy. Last thing you want in an electric motor is conductive fluid between the stator and the field coil.
Fluid in this area would serve no purpose as trans fluid is a poor coolant and really nothing to lubricate there except the thrust bearing. Plus there would be sealing issues as the windings egreess the housing assy as the power leads to the Inverter.

Which leads me to believe that the windings are not exposed to the trans fluid at all. I went to Youtube and found a few Prius trans teardowns one in particular that shows both MG1 & MG2 are in sealed dry separate chambers in the trans. MG1 on one end and MG2 on the other end and the planetary gear drive system in the middle in a separate chamber.Thats where the fluid is only. In the gear drive chamber. Very clear in the video.
Strictly GL4 gear lube. Doesn't come anywhere near the motors or the windings. Which makes perfect sense.

In the video you can clearly see the field coils have the standard bell wire coating and terminate to bolt lugs where the external leads are connected to egress for the separate mg power leads. One for m1 and one for m2.

 

i call BS on this. anyone with used oil and multi-meter should be able to dispel that. i'll try that this evening.

 

YES!! "nasty metallic brew"!!!

Oil is conductive if its contaminated. Think 8 years of hard gear lubrication.

You can clearly see both mg's are in clean sealed chambers with the lubricated sun gear system in the middle. As noted the mg magnets are very powerful and the air gap between magnet and field coil would be covered in a nasty metallic WS slime if exposed to 200,000 mile trans fluid. I mean manual gear lube because thats all the fluid is used as. That would be a nightmare to contend with for the designer. And would greatly affect the motors performance. Toyota fixed that. It keeps the fluid nowhere near the motors and winding's. As far as coolant is concerned they show that area also. Very small heatsink area on the outside of the mg2 case assy where the coolant flows through channels just like in the Inverter. Apparently high heat is not a factor in this excellently engineered trans and WS is not there to be used as a coolant. Its gear lube.

As far as the fluid not being conductive your thinking 9 volt fluke ohmmeter conductivity. Try 300 volt ac conductivity because thats the world the fluid would be exposed too if around the armature.Put 200,000 mile fluid in a bucket and put the ohmmeter probes in the fluid. It may measure meg ohm conductivity maybe lower and not very constant. Now put metal probes in the bucket and put a 300 volt ac with 100 amp potential across them. Like a megger. I guarantee you'll have a much better result.

Btw, magnets are practically bulletproof.The windings are the weakest link. When the Prius fails its from winding blow out never any magnet damage. Whats to damage?

 

First, I like the video:

I didn't see any oil seals. My experience is the oil serves to remove heat from the stators as documented by the Toyota SAE papers. The original NHW10 had oil seals but they were dropped with the NHW11 to reduce internal friction losses.

I won't rule out oil causing some stator failures BUT a better hypothesis is a void in the potting compound led to coronal discharge that eventually 'ate' the potting compound and wire insulation. Once a short formed, the stator would cook itself.

Source: SAE Technical Paper Series 2000-01-C042, Development of the Hybrid Vehicle and its Future Expectation, Shinichi Abe, Toyota Motor Corp., Detroit, Michigan, October 16-18, 1999

. . .
Mechanical areas: (1) reducing the oil pump loss, (2) reducing the oil mixing loss, and (3) reducing the motor drag loss through the elimination of the oil seal.
Electrical areas: (4) changing the power output and torque by changing the motor windings and magnets, and (5) changing the motor control.
With regard to the motor for the previous Prius, the gear section is separated from the motor and generator chamber to prevent transmission oil from entering the motor (generator) chamber. However this is not favorable in terms of fuel efficiency, as the sealing structure increases dragging torque.
. . . ​

Bob Wilson

 

So in the meantime......the rest of you go change your tranny fluid at first 10,000 miles and every 30,000 after that.

 

My recommendation on transaxle oil changes:

• with first oil change at 2-5,000 miles
  • removes initial manufacturing debris for all but ~15%
• at 15-25,000 miles
  • dilutes the ~15% to ~2%
• at 75-150,000 miles there after (optional)
  • dilutes any remaining wear material

Bob Wilson

 

i'm glad i didn't waste my time doing measurements because you just found an excuse to reject any empiric data.
i take you up on the I guarantee you. show us the (300V) data please. if not, you're just talking through your arse.

 

I've been intrigued by this discussion for some time - but never chose to change the fluid. I just sold my '05 with 208k miles...on the original trans fluid. In fact, the only part ever replaced (outside of recalls and such) on the car was the front wheel bearing at about 195k. Oil at 5 - 7k, coolant at each 50k, plugs at 120k. Just a datapoint, nothing more.

 

Gen 2 has proven to be a solid build. We will see how the 3 pans out over time. Except for the engine knock issue all of mine seem to be perfect. Also have not seen the start up knock for about 9 months.

 

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