Suitable substitutes for the Toyota ATF-WS transmission or transaxle fluid?

I'm nearing nearing 30,000 miles on the Redline I put in, I will be sending a sample off for an analysis at 30k exactly, hopefully I'll get some good information on exactly how the Redline performs. It's a racing oil that should be preventing wear more than the standard WS, but the oil analysis will show that one way or the other.

 

Just to satisfy my scientific curiosity, would you mind asking your lab if they can do a dielectric strength test? I would gladly reimburse you beforehand. You might need to send in a larger sample for that test. A test of unused ATF for comparison would also be interesting, if you have some left over.

 

I'm using blackstone, I'll shoot them an email. I'll also ask them if they have the original on file, if not I'll send in a fresh sample for them to check out. Should be very interesting to see what comes back.

I do know after 70,000 miles the Toyota "lifetime" fluid was disgusting. I can't fathom how it's supposed to last 100,000+ more miles on that....then again the warranty on the CVT ends at 100,000 miles I believe....so that's likely the lifetime they were reffering to.

 

That would be great if they are able.

It's a very robust transmission with no finicky things like synchro-rings, clutches or solenoid valves. I think it takes about 200k till the ATF is really shot, then another 300k till the transmission slowly chews itself to pieces. The way you drive, a bit sooner.

 

What bothers me: maybe your alternate fluid looks fine, but what's happening inside the transaxle? Maybe nothing, but maybe something? Toyota is adamant on this, that nothing else should be used, or risk damage.

 

I asked Mr Weber a direct question is the fluid separate on a G2 from the diff section and does the fluid ever touch the windings?

His reply:

According to Mr Weber only the G3 has the atf touching the windings. Not sure why.

It makes no sense for the fluid to interact with the windings especially if your trying to cool something like that.

Cooling only happens with some type of heat exchanger like a rad where the heat is removed. The G2 has no ATF cooler only its Inverter coolant which is routed through extensive little chambers surrounding the 2 stators and is cooled by the bottom section of the radiator. And it does a very good job of cooling. There is no atf cooler in the G3 afaik.

 

Well, at least we can all agree on that, which is fortunate, since we are here in the 3rd Gen subforum. A discussion of why, could easily fill another long thread.

So although the ATF does come in contact with the uninsulated high voltage connections of the stator, that is generally not a problem, because ATF generally has a high dielectric strength. An exception that proves the rule might be, for example, an ATF with a high concentration of graphite particles, which might conceivably drastically reduce its dielectric strength.

 

Atf that has a some miles on it is a very poor dielectric. When atf gets black thats metal in solution.More black it is the more it can conduct.
Thats metal there.
Not a perfect conductor but at 500 volts it will do nicely.

ATF has a completey different life than transformer oil .T Oil see's no wear. Its just used as a coolant and has a dielectic base. ATF is not a dielectric becasue of the life it leads.

But it really doesnt matter if the fluid has dielectric properties (which it does not) becasue as long as the conformal coating on the windings is intact and there is no bare copper winding exposed to the fluid everyhting is fine. But if you even have a pinhole in the coating exposing a puin hole sized hole to the the fluid it will probably flash over at the current and voltage MG2 see's. I can guarantee you no part of the EXPOSED high voltage wingdings on a G3 is exposed to the fluid. The car would throw a ground fault intermediately.

So the whole dielectric discussion is moot and quite silly. Electrically the trans could care less if it has black atf in it. As long as the coating is intact your ok. If the coating has failed You could have transformer oil in there instead of atf it will still flashover.

 

I am talking about the uninsulated connections that you can see at 23:58 at the far right in the video below. It looks to me like the transmission fluid can slosh or spray up to them, or at least they will be wetted by the fine mist that develops throughout the transmission at higher speed. They are spaced so widely that only a weak dielectric strength is required.

But still, I want to emphasize that in any case, we both agree that an ATF with special dielectric properties is not necessary.

 

Fair enough Fred.

 

If you read alot of forum entries, on Toyota sites other than Prius, you will find complaints about WS and it's vulnerability to heat. Remember, It's not synthetic and many so-called oils and lubricants claiming to be synthetic are actually SAE Group 3. 95% of Synthetic lubes are Group 3 which are not SAE Group 4 which has a true synthetic base. So stick with Amsoil ATF, Royal Purple, or my choice - Redline D6 which is a true synthetic ATF that exceeds all the WS specs. It will last longer. cool better and quiet down the regen gear noise most Prii make. Available on Amazon for about $50 a gallon. I have it in 3 Prii now with no problems. WS really comes from Aisin, the tranny maker. It is usually cheaper than the Toyota WS. Still not synthetic.

 

My Prius runs really nice on d6. Exceptional trans fluid.

I run Redline 10-30 motor oil also and that makes a remarkable difference in quieting down the motor
And smoothness. Very noticeable.

 

Just for clarity: I bought Aisin WS tranny fluid from Rock Auto for my last change. I had a partial quart of Toyota fluid left over from the previous change, and compared the two. I assumed they would be identical... they are not. The Toyota fluid was much brighter red. Obviously I have no idea what the chemical/additive differences are... but they are definately not the same fluid with different lables as I suspected they would be.

 

What color is the.Aisin version ?

 

The Aisin fluid is red too, just not as intense in color.

 

Danlatu is right about LV.

 

Hello dear substituters and OEMers, I just happened run across this while sifting through my old files for @Dxta :

"With regard to the motor for previous the 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.

The resin material has been changed in the improved motor for the new PRIUS to enhance the oil resistance of the motor body; therefore, the oil seals are no longer required and friction of the bearing is reduced. This leads to reduction of mechanical loss."
​

Development of Electric Motors for the TOYOTA Hybrid Vehicle “PRIUS”
Kazuaki Shingo, Kaoru Kubo, Toshiaki Katsu, Yuji Hata
TOYOTA MOTOR CORPORATION
https://attachments.priuschat.com/attachment-files/2018/01/138195_evs17priusmotorpaper_shingo.pdf

 

I'm using the same Redline D6 in my 2010 transmission for the past 8k miles. So far it's running smoothly.

Pixel XL ?

 

So they've eliminated a seal, allowing the fluid into wiring area, and improved the wiring insulation. Also then, the need to stick with Toyota ATF-WS since this change is more imperative?

What would "the new Prius" be, 3rd gen (2010)?

 

As I understand it, the "new" Prius without the seal and with oil resistant insulation is the 2000-2003 Gen1, and the "old" Prius with the seal is the 1997-1999 "Gen0" which was available only in Japan.

My reasoning would be that it is neither before nor after imperative to use only Toyota brand ATF, since either the ATF has no contact with the windings, or the windings are ATF resistant.