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

Agreed. Car has 174k on it right now and the fluid has been changed twice so far. I actually like the fact it's slightly thicker at temp then WS as well. Better protection for the duty cycle the car sees and no measurable effect on MPG.

 

Hmm, somehow I missed this reply a year and a half ago....

I've just spent not quite ten minutes (I bumped the speed up) watching those ten minutes of the video to see where he said that, but I don't believe he said the base stock doesn't matter, or even that the additive package matters more. What he says turns out to be here:



and all he appears to be saying is that the base is not the only thing that matters.

What you're looking for is a product that passes a particular whole suite of tests specified by a manufacturer. Simply being told that a product is synthetic doesn't tell you that.

Even if a product would have to be synthetic in order to pass all the tests (which might be the case), just being told "hey this product is synthetic" is nice to know but not enough; the question is still "does it pass all the tests?".

It's like if you're deciding whether to accept a $100 bill from me, and you know it had better be printed on rag stock, with green and black ink, and signed by the US treasurer and treasury secretary.

If I hand you a thing printed on rag stock, that by itself doesn't make it a $100 bill. In saying that, I'm not saying the stock doesn't matter, and I'm not saying the ink matters more. I'm just saying it's not a Benjamin unless all the specifications are met.

 

If Toyota ATF WS standard was developed in 2002, then it wasn't designed to protect the MG windings paint insulation, because it wasn't in contact with it before Gen 3 or ( 2009 )

I have done 2 oil changes with Mannol ATF WS, on my 270k km prius 3 ,the last time in 2022, but today there is no way to find it anymore in 1 or 4 liters bottles.

I can only find warehouse left overs of 10 or 20 liters jerrycans on Autodoc.

So yesterday I've done my last tranny oil change with Mannol Dexron 6

 

The cost difference is about a dollar. Why risk damage to the transmission?
Just because something or someone says it okay to use something else, who knows what
it's doing to the electric motors???
The "average" miles a year for most people is 12,000 miles. So you're changing it every
4 years.

 

Maxlife LV works well. Done many CVT fluid changes in Prius over many years on more than 2 dozen pri and no failures. Can't from wrong with dealer fluid, but this seems to be ok as well. I'll admit only dealer fluid is guaranteed to not cause problems tho

 

@Abarnabe is Toyota ATF WS hard to get in Netherlands?

 

it is available, but at the price of 20 usd per liter + 20 usd shipping

 

"wasn't in contact with it before Gen 3" is clearly false, given that Toyota published a paper explaining the change from not-in-contact in Gen 0 (the 1997 Japan-only car) to in-contact in Gen 1. The paper described the winding varnish being reformulated to resist the oil used in Gen 1 (which was T-IV, because ATF WS was still in development). That's all been discussed before, e.g. here. So the issue of oil-varnish compatibility was clearly on their minds during the period of ATF WS development.

So we know it's in contact in Gen 1, and we know it's in contact in Gen 3 (another Toyota document shows that). There are some people who seem convinced it was not in contact in Gen 2. I'm not sure I have slam-dunk documentation on hand to unconvince them, though it would seem odd to change from in-contact in Gen 1 to no-contact for Gen 2 and back to in-contact for Gen 3, and also the Weber Auto videos for Gen 2 show the same oil drainage ports below the MG windings that can be seen in Gen 3.

 

Buy Toyota Automatic Transmission Fluid ATF WS 1 L at ATO24 ❗

 

Found a document about thermal management of Gen 2 Motor Generators and indeed the oil is used to cool them off on page 4.
in Gen 3 oil is splashed by gears on to the windings.
In Gen 4 it is pumped directly on to the windings, this would explain why gen 4 can tow up to 750 kg, while gen 3 officially can't tow anything.

 

Thanks! From DoE rather than directly from Toyota, but seems like enough to settle the question re: gen 2.

 

I tow a 4k lbs boat and at wot do 65 mph on level ground without triggering thermal safety for mg1/2 coil temps. Have 275k miles on two pri I own and treat them both this way. No bad CVT assy's this far. Using maxlife LV. Small sample size I know. This might suggest this fluid is acceptable but far from scientific evidence. If u need a substitute, this works for me

 

To close the debate, Aisin who makes Toyota transmission, makes its own ATF it is Called ATF 6+ FE. It is compatible with almost any car makers including GM, Ford, Dexron VI, Mercon LV,etc.

It concludes the rumors. Valvoline Mex/Merc claim is legit, it is trully good value compatible ATF for Toyota WS.


https://www.aisinaftermarket.eu/wp-content/uploads/2025/05/PRODUCT_SHEET_ATF_6FE.pdf

Aisin also makes or re-bottles ATF6 which is compatible with Toyota T-IV fluid or Dexron IIIH, higher visousity fluid.

 

It would be interesting to get Prof. Kelly to update his ATF comparison to include that stuff.

I've looked over that product sheet myself, and seen the list of a dozen ATF specs on the back under the heading "performance levels", but I am not certain whether I should read that as actually claiming to have been independently tested and approved under each of those specs. Other products in the past seem to have used similar kinds of wording over lists of specs they never quite actually said they'd been approved under.

I remember in Prof. Kelly's video he reserved particular unflattering attention for products whose long lists of specs would include specs that were mutually incompatible. I would have to defer to his knowledge on whether this is or isn't another example of one of those.

 

Yes, I love Prof. Kelly channel. He is a very good teacher. However, in terms of Oil, tribology, or lubricant, he is not the expert. There are a few of oil expert like Lake Speed, The Motor Oil Geek is trully educate us with real Laboratory and certification test for engine oil. We can ask him about ATF. He probably know more about additives in ATF.
For engine oil, there are more less only 4 in the world who make additive package: Afton Chemical, Lubrizol, Oronite (Chevron), and Infenium (Shell Exxon).
It is probably the same with ATF additive formulations. There is a good reason why TESLA also use Dexron VI. It is easily avaiable and open for 3rd party certification unlike Toyota T-IV and WS.

 

It never works like that.

maybe it’s human nature, when someone says do “A”, you’re inclined to do “B”?

 

Ja, I think I am saying it to myself. It was my own conclusion and I assume the debate is closed for me.

 

What stil intriguing is if Toyota WS can be used in T-IV just like how Dexron VI backwards compatible with Dexron III.

GM claimed that Dexron IV has less initial viscosity than Dexron IIIH, but it is more stable and over the usage period, Dexron III fluid is often has lower viscousity than Dexron VI.

It will be great if someone knows the details of the oil additive packages requirement for Dexron VI and Toyota WS. I know both are mildly absorb moisture from air as any oil with some polar additives.

 

I don't have the doc handy at the moment but IIRC Toyota's answer was 'no'.

 

I agree. I prefer to use Toyota T-IV or Dexron IIIH in older transmission instead of Dexron VI or WS because I change the fluid regularly. The viscousity level will not be lower than WS before I drain and refill it every 60k miles.
Toyota transmission with T-IV like 5 and 4 speed AT are tough, really-really tough.