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

I don't put much stock in the hybrid components degrading fluid electrically or that special fluid is needed to protect them. Yes, Toyota took care in segregating the windings from the lubricant. People are assuming that WS ATF has some magical component that protects this resin rather then taking the viewpoint that the goal was to keep ANY lubricant out in general. Since the primary difference between conventional transmissions and hybrids is electricity people are running with the theory that the fluid has to have some special properties that help these components. Nowhere is there evidence this is actually true. To the contrary, there are people running Amsoil, Redline and more predominately Valvoline MaxLife without issue. As has been stated, failures in a Gen 3 transaxle are at the bottom of the list of things that sideline these cars.

If you disregard all the hybrid components, at the end of the day, there is still a commonality with every other FWD transaxle out there. That is a differential that is going to squeeze and shear the hell out of fluid as it transfers power. Conventionally, a 30K change interval used to be the norm for changing differential fluid. Prior to manufacturers covering maintanence BMW used to recommend transmission and differential fluid changes at 1200 miles to remove break in debris.

Bottom line is that the fluid goes through heat cycles in everyday use and most likely tracks fairly close with the temps MG1 and 2 are running at. This effects the fluid chemically over time. Additionally, the fluid is compressed as it pumped through the transaxle and squeezed and sheared as it helps cool and lubricate all the gears in there. All these are what is going to degrade the fluid over time.

Here is what the inside of a Gen 3 transaxle, transmission, HSD, power split device or whatever people want to call it looks like...

 

From the technical article referenced the resin, (my apologies didn't catch the spelling difference my son uses rosin on his cello but this one is "resin"), was improved to resist oil (I'm assuming the WS in this case), so that the separation was no longer necessary...

I noticed there is no language like WS was chosen due to electrical resistance nor resin compatibility...

REVVL V+ 5G ?

 

The only way we could agree to that would be if a laboratory test showed the WS had recognizable components of the resin dissolved in it. The mere fact that we know they changed a previous resin formula, to be more resistant to the lubricant they were testing with, is not evidence that the later resin formula dissolves in the same lubricant. That would be strange indeed, if that was just what they reformulated the resin to avoid.

They don't keep the lubricant out. They did in Gen 0, but eliminated that seal friction for Gen 1. Instead, they reformulated the insulating resin to be more resistant to whatever lubricant they were testing with, so they would not need to keep the lubricant out.

You are certainly emphasizing the common aspects between the Prius transaxle and other FWD transaxles. We do know those aspects are common.

We also know that the hybrid aspects hidden behind your "if you disregard" are aspects that are not common between the two types. The other FWD transaxles do not have HV electrical windings in them. That's not an assumption, it is a difference we know about.

We know that compatibility of the electrical insulation, with whatever lubricant they used in testing, was something they had to engineer for, and involved at least one reformulation of a resin. That isn't an assumption, it's something we know from what Toyota published about the transaxle's development.

We don't have a statement anywhere (that I've seen) saying WS is for sure the only lubricant compatible with the resin they developed. We could assume that all lubricants are equally compatible with it, even ones not tested for that property, which isn't part of conventional transaxle lubricant testing. That is what you're assuming, and it might turn out to be a perfectly ok assumption. It's just worthwhile to keep clear about what is and isn't being assumed.

 

Out of contact with the windings vs out the case would have been a better way to put it.

I was trying to get at why the fluid would degrade outside of the vehicle being a hybrid.

Yes, it's been discussed that the resin was a consideration. Personally I believe the resin was what was reformulated to fit the application, not that WS was created so it could be used in the Prius. Others believe that the owners manual admonition that only WS be used is proof that the fluid is needed in the hybrid and those of us who use other options are risking serious damage. None of us have direct evidence to make this more then opinion.

What I'd also note is that there is no evidence that WS, err world standard, ATF was specifically engineered for the Prius. I would find that quite surprising actually. The spec was released in 2002 and showed up in numerous applications for the 2004 MY. I think it's more coincidence that was the first year for Gen2 rather a smoking gun that WS was developed for the Prius and it just happens that Toyota used it in their most popular transmissions and transitioned all the conventional automatics over to it.

As has been previously noted, other manufacturers released similar fluid specs, Dex VI, Mercon LV and ULV, Kia/Hyundai SPIV etc... A more stable, longer lasting, low viscosity fluid was where the industry shifted too

 

Still, if it isn't kept out of the area, as it hasn't been since Gen 0, it's only the resin on the windings that keeps the lubricant "out of contact with the windings", if that's the way you want to say it. Hence the reformulation of the resin.

It's clear that WS is used in many Toyota vehicles and not something specific to the Prius. For that matter, the resin was reformulated between Gen 0 and Gen 1, which used T-IV, not WS. So addressing whether "WS was created so it could be used in the Prius" seems to be a straw man, a response to something that isn't proposed ...

... and so many words addressed to a straw man may only muddy the water.

The owners' manual admonition is there. If someone, say Mendel, points it out, that may or may not tell us a lot about what Mendel personally believes. He might, for example, believe that it's worthwhile mentioning what the owners' manual says, in a PriusChat thread where people will come and read about the topic.

The "risking serious damage" bit isn't coming from Mendel, it's right there in the admonition that's right there in the manual. Again, nothing much really hinges on whether he personally thinks that passage "is proof that the fluid is needed in the hybrid", or maybe just that readers of the thread deserve to see it themselves.

Pretty much everything is opinion, but opinions aren't atoms; they can be examined to see what assumptions were needed to arrive at them.

Remembering the things we do know:

• a Prius transaxle has aspects that are common to conventional transaxles, plus at least one aspect that's distinct
• one distinct aspect required an engineering effort to formulate a resin for resistance to (at least some kinds of) oil
• polymer resins are often messy formulas of hydrocarbons and other stuff, and so are oils, and interactions between them can be complicated and require testing individual combinations

it is possible to assume that other oils, not specifically tested against a requirement conventional trannies don't have, will still perform equally well on that requirement, or well enough that it won't matter. You're free to make that assumption; you don't need anybody else's permission, and it could turn out ok.

By the same token, if there are others choosing not to make that assumption, that doesn't mean they have to be assuming the opposite is true or proven. They might just prefer to avoid the assumption.

 

Interesting. I didn't catch that the memo was about Gen 0 and Gen 1 and thought it was about Gen 1 and 2. No clue Gen 0 was a thing until you mentioned it. That little tidbit and Gen 1 using T-IV just reinforces my opinion about the fluid not needing to be anything "special" to protect the resin and that Toyota's owner manual admonishment is nothing more then typical legalese to potentially limit warranty liability if needed.

 

Again, you are free to assume that fluids Toyota was not testing with, while specifically reformulating a resin to be resistant to some fluids, will perform as well on that measure as what they were testing with. I agree we have no smoking-gun evidence showing that assumption is wrong.

Others may, nevertheless, prefer not to make it.

 

I definitely skipped some parts and glazed over on some parts of the article. Definitely did not catch which generations they were referencing. Thanks for clarifying!....

REVVL V+ 5G ?

 

Valvoline is sending us a clear message - their Maxlife ATF bottle recommends their product is compatible with myriad fluids that are supposedly incompatible with themselves....we're overthinking it. They're sticking their finger in the eye of the manufacturers who want to give their dealers another way to milk customers.

Toyota has done an AMAZING job of hiding the details about WS. They could easily say "WS has a proprietary electrical protection property", or some other clincher....but they don't. I'm impressed with their success. They are entitled to say "If you don't use WS you could damage your transmission". That will always be true.

How many Prius owners use Toyota branded motor oil....just to be safe?

At the end of the day, driving a Prius is about saving money, and staying out of dealerships. As of this writing, a quart of WS at my local dealership is $13.03. A quart of Valvoline Maxlife Synthetic ATF at Walmart is $4.64 with the rollback.

 

The fluid is changed out every 60k miles or more. Not sure why paying $40 more for that many miles would even be an issue. However putting in the wrong fluid and paying $3000 for a transmission might be an issue for many that are trying to save money with a prius

 

Maybe true on your findings. I never even thought about using other oil on transmission. I went to the lab and checked my transmission oil after 35,00 miles. There are already lots of breakups and contaminations. Next time Ill change mine on 30,000 miles. (that's just me)
In regards to engine oil, I just use an "okay" quaker state 5w-30 synthetic oil. Since my car is over 150,000 miles, I went down from 5,000 miles change oil and filter to 4,500. I notice the mpg is not the best atleast I can get anywhere from 43 to 45.5 mpg depending on where I'm driving. I'm hardly losing any engine even after 2,000 miles which is not bad for an 07 car. I don't have any catch cans or basically all in stock configurations. The only thing I'm really watching are the timely maintenance especially avoiding overheat. I changed all 3 electric cooling pump and 1 mechanical water pump plus the thermostat and a full flush at 100,000. Knock on wood, I hope I can still get another 100k miles in this car before it dies.

 

Milking owners buy telling them don't need to change it?

Toyota advises to use a specific Toyota fluid (in the Owner's Manual) in only one instance, the transaxle fluid. And strongly cautions that alternates may damage the transaxle. For a few bucks, every 50K miles or so...

 

USE 3 in 1

 

There's another way of reading Valvoline's message. The tenth video in this Weber State University playlist touches on it.

The History of Automatic Transmission Fluid - YouTube

Valvoline MaxLife can be seen by skipping to 30 minutes in.

 

Yep....that was the strongest case to stick with WS that I saw.

I love John Kelly's video's. But he kinda lost me with his views on Valvoline (founded in 1866, factory fill for the Ford Model T, and with us every step of the way since). When he suggested that Valvoline is running a racket and that, with regards to ATF, it doesn't matter which base stock a manufacturer uses - dino or synthetic - that was where we parted ways. In 1945 Valvoline developed a single grade oil, called X-18, that eliminated the need for 18 other specific lubricants. In 1954 they created the first all-season car oil, and it goes on and on. That's what Valvoline does - I have a hard time believing MaxLife ATF is a racket.

But I still think his video's are great.

 

Do you remember at what point in which video he makes that suggestion? I don't remember it, but they're long....

Could his point have been maybe that it would be ok to make ATF out of rabbit snot if you could actually make it pass every required test in the currently applicable manufacturer specs?

 

Transmission fluid is different than engine oil.
Toyota's transmission fluid is made and designed for their transmission.
Other manufacturers "may" produce fluid that is similar, that doesn't mean it's the correct
fluid and is best for the tranmission. The cost difference is minimum.
Not worth risking damage to an expensive part of the car.

But, it's YOUR car.... YOUR money...

 

So, a quick update. Now at 130k of using the "wrong" fluid in my car. No failures yet.

 

Dealing with "risk" is a debatable thing. If you take a prudent course, follow Toyota's emphatic warning, your odds are very good you won't have an incompatible fluid, or something adverse happening due to the fluid. If you use an alternate fluid, you may well also be fine. Myself, this is one time I'd rather not be the rebel.

 

Any approved Dexron VI/Mercon LV ATF will perform well for WS fluid requirements. Dexron VI standard is overall really good and exceeds WS specs for stability and long terms viscosity and antiwear additives. Just makes sure it is officially approved Dexron VI that Tesla and all other EV cars used. Dexron VI is like Android OS and WS is like Apple OS.