Automatic gear oil change is a topic that confuses!

Discussion in '3rd Gen - 2007 - 2017' started by sulatek, Jan 9, 2020.

  1. TobyU

    TobyU Full Access Members

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    The first guy is useless but chrisfix is fairly accurate but he highly contradicts himself when he says that changed the fluid can't damage your transmission. He claims it's already damaged. That is true BUT the damage is that it's warm and has a lot of grit in there. It is damaged however it is still moving the car and not slipping.
    He even says this in the next sentence. That adding the new fluid could cause it to slip. So he personally doesn't consider causing a transmission to slip damaging it but most people would.
    The simple fact is that if you have a transmission with the dark black gritty fluid and the clutches aren't slipping at all , they might start slipping if you put fresh fluid in it. They have an even greater likelihood of slipping if you flush the transmission.
     
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  2. TobyU

    TobyU Full Access Members

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    Also, the owner's manual will not always tell you whether to change or flush. However, almost every dealer will tell you to flush.
    I do like him and it is the best video I've seen on transmission flushes but there are no exact answers on this.
    He even says might several times. That's because it's not an exact science. He does point out that you're probably not going to have problems unless your fluid is very old with high miles and very dark and gritty but the point is the shades of grey in between!
    There is simply no exact way to know that fluid a is okay to flush or fluid be is not and what if it's right on the line. There's always a chance.

    Also, his comment about the gritty particles allowing it to operate goes back to my comment about Shady used car dealers putting sawdust in the transmission.
     
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  3. sulatek

    sulatek Active Member

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    Shady used car dealers putting sawdust in the transmission.

    this should be called " a crime " !
     
  4. TobyU

    TobyU Full Access Members

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    I think it was- fraud- but could never prove it.
     
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  5. sulatek

    sulatek Active Member

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    Yes ,
    My point of view that " cheating is a Crime "
    anytime, anywhere
     
  6. coupe11

    coupe11 Full Access Members

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    How does the pump circulate dirty/gritty fluid with a filter in place? How does it keep from wearing out the pump?
     
  7. TobyU

    TobyU Full Access Members

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    When the particles are small enough some get through and who knows if 100% of the fluid gets filtered anyway in all transmissions.
    There is a point that it would clog up and not work though. I had a old 68 Pontiac one time I had been driven pretty hard and had about 155k on it but was about 20 years old at the time. It started holding in gear longer and wouldn't shift and would Surge and buck a little bit while it was trying to shift and if I would let off would usually shift. I change the fluid and filter and it was fine. I assumed the filter was quite clogged up and couldn't get any flow.
     
  8. Wangle

    Wangle Active Member

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    My brother in-law bought a used vehicle with 160k miles, facing this same dilemma. I encouraged him to do a fluid change, no flush. He opted to let it go. My sister totaled it at 165k. He won! Point being you are rolling the dice. If you change it you MIGHT never have a transmission issue. Best odds... change fluid, filter if accessible. Never flush.
     
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  9. Machete

    Machete My Rig. 2000 EB 4x4 5.4L

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    This is a fallacy. First, the flush removes any debris and secondly the flush removes all the old fluid where a drain and fill leaves several quarts of the dirty fluid in the tranny.

    My 2000 has 200k and I flush it at the dealer every other year.

    Smooth as silk.
     
  10. TobyU

    TobyU Full Access Members

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    Not a fallacy but the above is not what happens.
    You flush your trans often so no harm. We are talking about not high mile ones but ones that are neglected and never changed ir flushed until they have high miles like 125-150+.
    It is not that any particles wreak havok. It is that the clutches are worn and worn in just right...or right enough to not slip.
    The trans is used to the stickier fluid with the grit enhancing friction grip of the clutches (variable line pressure and such)
    The fresh fluid and getting a lot of the grit out from even pan drop and fluid change can and has caused the clutches to not be able to grip in a few days or so.
    A flush in this situation is even more risky as it removes much more of fluid and washes the clutch packs off more.

    Any trans that fails shortly after a flush or fluid change was not in very good shape and was short on life BUT it wasn't going to start slipping in a few days to weeks.
    Maybe 6k-10k more or longer but the flush is the catalyst that really speeds up its demise.
     

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