Is this a marketing gimic or is it essential for transmission fluid change?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Priipriii, Oct 22, 2025 at 7:00 AM.

  1. Priipriii

    Priipriii Member

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    So id like to swap out my transmission fluid on my 3rd gen prius. I dont think its been changed ever and its already 15 years old with three vehicle lifetimes worth of mileage. Question is, which fluid would you guys recommend? I found this one that is specifically marketed towards hybrids (see attached pics). Is this worth the extra dollars compared to conventional ATF or is this creative marketing of a 'premium' product? All in all itll only be $10 extra but i am just curious if there is actual any benefits to it or just snake oil.
     

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  2. BiomedO1

    BiomedO1 Senior Member

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    IMHO; Everything wears out and the car is out of warranty - so technically the fluid has fulfilled it's lifetime commitment.

    The OEM stuff lasted 15 years - Do you want to take the chance on that stuff?
    As you stated; you got 3 lifetimes out of the OEM stuff, so if you kill it on it's fourth life with this stuff. No big deal????????????

    Just thinking out loud and my two cents...........

    PS; Can you take a sample and sent it out for testing? Include some new stuff so we can make a comparison.
     
    #2 BiomedO1, Oct 22, 2025 at 7:28 AM
    Last edited: Oct 22, 2025 at 7:48 AM
    ASRDogman likes this.
  3. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    It's not a transmission.
    It's not a transaxle.
    It's a 'power-split' unit, and they're mostly a "Prius" thing.

    SO.
    Why not just get use the fluid from the mother ship?
    Yeah....
    I get it.
    A BUNCH or reasons!!!!

    The dealerships are crooks.
    Toyota is NOT a very nice company to deal with when it comes to acknowledging MAJOR FREEKIN design flaws in their car.
    However (comma!!!)
    You want to know WHY in this one, specific case that you want to use the gen-u-wine Toyota "atf" fluid???

    Stator Windings.
    Priuses have them.
    LOTS of hybrids do....
    upload_2025-10-22_7-31-53.png

    The "power split" device in your car has them, and it's important to keep the insulation from breaking down and causing electrical problems.
    We saw this a bit in the G2s back in the day.
    There are probably other items in the transaxle/power-split device/transmission that might be contaminated by some mystery-fluid.....
    SO!....this is one of the few times when I would just use the factory stuff and get on with my life.
    NOTE!
    When you said that YOU would like to replace the fluid I presume that you meant YOU would be doing the work.
    If not - you will need to know what's involved in replacing the fluid so that you can check the work of whomever you hire to do it for you.
    It's a pretty simple job.
    Probably a "2" on the 1 thru 5 ETC(SS) Maintenance Difficulty Scale (TM) but it is important to do it correctly or you can trash the unit - which is probably why the greedy sap suckers at Toyota didn't feel like adding it to their maintenance schedule.

    Toyota claims that their "ATF" [sic] is a 'lifetime' fluid - which is accurate.
    It will last for the lifespan of your 'transaxle' [sic] but the fluid that THEY USE is at least backed by them for the warranty period of your car.

    Whatever "hybrid recommended" mystery fluid (snake-oil, probably) that you use is ONLY guaranteed to last for the lifetime of your car's 'power-split' device.
    TIFWIW......

    Remember also:
    The 'power split' device is a sealed unit and there's no combustion happening in there.
    The ENGINE is another matter, and a 15-year-old G3 has a LOT MORE PROBLEMS than a transaxle/transmission/power-split device that still has all of it's original fluid!!!!!

    That takes us back to the fact that there are major design flaws (plural) that Toyota has not mitigated with the G3s.... ;)
    Like.....their "lifetime" head gaskets and EGR circuit.... :LOL::ROFLMAO:
    Good Luck!
     
    #3 ETC(SS), Oct 22, 2025 at 8:44 AM
    Last edited: Oct 22, 2025 at 8:52 AM
  4. ASRDogman

    ASRDogman Senior Member

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    You think 5 years is a "lifetime" for a car???

    And you want to pay $10 more to get only a 95% chance it will work when you have a 100% chance
    the OEM fluid will work, for $10 less???

    I agree with Biomed01.....


     
  5. Georgina Rudkus

    Georgina Rudkus Senior Member

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  6. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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  7. Tombukt2

    Tombukt2 Senior Member

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    That fluids fine for me over 209K on it . Ship it. I keep my cars . So I know because it's right they're.
     
  8. Georgina Rudkus

    Georgina Rudkus Senior Member

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    Still, I'll use Toyota WS.
     
  9. Mendel Leisk

    Mendel Leisk MMX GEN III

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    Toyota says in Owners Manual, that anything other than the spec'd Toyota ATF-WS fluid could damage the transaxle. Your response: how about this stuff?

    FWIW, you're not alone: lots here advocate "better" fluids. Who knows.
     
    #9 Mendel Leisk, Oct 22, 2025 at 12:55 PM
    Last edited: Oct 22, 2025 at 2:26 PM
  10. PriusCamper

    PriusCamper Senior Member

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    It's probably worth trying so we can find out... It's not gonna cost us anything. :) And I remember researching this when I first got my Prius. There might be some additives in the fluid design for transmissions with electric motors, but until we do a comparative analysis of what each fluid has in it, there's no way to be certain. But if I had to be on it I'd place my bet on there being no difference.