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Transaxle Fluid. Do I Change It Or Leave It Alone?

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by Lexington-76, Sep 13, 2024 at 11:46 PM.

  1. Lexington-76

    Lexington-76 New Member

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    Hi All

    I’m trying to figure out if I should change my transaxle fluid or leave it alone. The manual say only inspect every 30,000 mile but doesn’t say when you should change it.

    I watch The Car Car Nut on YouTube and he advise (at least for the Lexus), that if you haven’t changed your transmission fluid before the 100,000 mile mark don’t change it and leave it alone. Well I’m at 100,000 and I’m trying to decide if I should change it or leave it alone. My assumption is that since the car is a Hybird that the transmission doesn’t work as hard compared to a normal gas engine car. Any advice here would be appreciated.

    Thanks
     
    #1 Lexington-76, Sep 13, 2024 at 11:46 PM
  2. BiomedO1

    BiomedO1 Senior Member

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    Welcome Lex;
    The car nut is speaking about a normal transmission with valve bodies and wet clutches NOT a hybrid CVT.
    I'm of the opinion that you should change it, just to remove the break-in wear material and other nasties floating around in there. Actually your transmission is working harder than a normal transmission, because of the two electric motors within. Your transmission may work independent of your ICE and move the car up to 10 mph before requiring the ICE to kick in.
    While the transmission on these cars don't fail too often, I just like to give it a leg up and consider it cheap insurance.

    Hope this helps....
     
    #2 BiomedO1, Sep 14, 2024 at 6:26 PM
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  3. ColoradoBoo

    ColoradoBoo Senior Member

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    I agree, go ahead with the change....it's as easy as doing an oil change BUT be ready for very tight hex bolts if they haven't been open in 12 years. (My Gen 4's have 10mm hex bolts.)
    I found it easier to snake a tube down the back of the engine bay to refill mine instead of pumping up the fluid...I hate those hand pumps.
     
    #3 ColoradoBoo, Sep 14, 2024 at 7:12 PM
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  4. bisco

    bisco cookie crumbler

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    if you are keeping the car long term, change it. if not, i wouldn't bother, these transaxles are almost bulletproof
     
    #4 bisco, Sep 14, 2024 at 8:03 PM
  5. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    The type of work matters a lot.

    The Prius transaxle does not contain any clutches, bands, belts, drums or other friction systems. Therefore no particles are ever shed into the fluid.

    This is fundamentally different from most automatic transmissions, and it's the reason why these cars can go a zillionty miles on the factory ATF.

    If you do change it, insist on the real-deal Toyota WS ATF. I'm sure many other ATFs would provide the right lubrication, but personally I would not take the risk that they might eat the insulation off the windings of the motor-generators in there.
     
    #5 Leadfoot J. McCoalroller, Sep 14, 2024 at 9:01 PM
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    About one year or 10k is about right for that. Then you can leave it much longer, say once more at 100k or 10 years.

    @Lexington-76: yes, by all means change it. There’s a relevant link in my signature; on a phone turn it landscape to see signatures.
     
    #6 Mendel Leisk, Sep 14, 2024 at 9:29 PM
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  7. Lexington-76

    Lexington-76 New Member

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    Thanks Biomed01. I staring to realize that the Prius transmission or transaxle is a completely different beast and I’m still trying to understand it. By the way, what is ICE.
     
    #7 Lexington-76, Sep 14, 2024 at 11:34 PM
  8. Lexington-76

    Lexington-76 New Member

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    It’s standard operating procedure for me that I always have a new set of bolts on hand just in case. I recently attempted changed the front differential on my 4Runner and just couldn’t get it off. Had to take it to my mechanic and they practically destroyed the bolts getting it off. I’ll let my mechanic do it for me.
     
    #8 Lexington-76, Sep 14, 2024 at 11:40 PM
  9. Lexington-76

    Lexington-76 New Member

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    How long we keep this depends on my daughter since it’s basically her car. However, I lost a Isuzu Trooper in the past because I didn’t keep up on the fluid changes. I’ve been a stickler on my maintenance ever since.
     
    #9 Lexington-76, Sep 14, 2024 at 11:44 PM
  10. Lexington-76

    Lexington-76 New Member

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    Again I learned something new fro
    Again I learned something new from you Leadfoot. Thank you very much. This explains why the manual says only inspect. If I change it I plan on only using the WS ATF.

    By the way, does anyone know what the average cost is for one bottle of WS ATF goes for?

    Thanks
     
    #10 Lexington-76, Sep 14, 2024 at 11:48 PM
  11. Lexington-76

    Lexington-76 New Member

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    Thank you Mendel!

    This is very helpful! So generally recommend changing it every 100k or 10 years.

    Out of curiosity, has anyone ever experienced any transmission problems after changing the fluid. It’s seems with normal transmission, replacing the ATF on older transmission can potentially cause problems but from what I’ve read here this doesn’t appear to be the case with the Prius. Is this correct? It also seems the procedure for this is a simple drain and fill with no special procedure or tools correct?

    Thanks
     
    #11 Lexington-76, Sep 14, 2024 at 11:59 PM
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