bad flush?

T

T man

Registered
just curious...

I was going to change my girlfriends tranny fluids but her dad told her not to have them changed because it could screw up her car since it has over 100k miles (probibly around 115k).

is there any truth to that? i noticed that she was low and I know she hasn't changed them since she got the car about 20k miles ago
 
T man said:
just curious...

I was going to change my girlfriends tranny fluids but her dad told her not to have them changed because it could screw up her car since it has over 100k miles (probibly around 115k).

is there any truth to that? i noticed that she was low and I know she hasn't changed them since she got the car about 20k miles ago
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Yes, it can happen and has happened to some folks.

New fluid changes the friction and temperature throughout the unit, making it operate differently. A worn or damaged unit may not respond well to working differently.

My opinion on changing your fluid is - I really don't know.
 
I guess I'd take notice of the words "My Girlfriend" and "Her Dad told her." He's probably not the one you'd want to get on the wrong side of. Just be prepared to bite your tounge if the thing eventually self-distructs. "I told you so" probably won't do you any favors either. :)
 
tixer said:
I guess I'd take notice of the words "My Girlfriend" and "Her Dad told her." He's probably not the one you'd want to get on the wrong side of. Just be prepared to bite your tounge if the thing eventually self-distructs. "I told you so" probably won't do you any favors either. :)
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Good advice...when in doubt, go with your friends. Wrong or right, it becomes win-win.
 
Dad knows best, it is better the change the trans then the fluid, if it was me I would change it.
 
I'd say it depends whether you want to keep her or not. (The girlfriend or the car - your choice. :p)

The preferred way is to drop the pan and change the filter and refill the system with only what was lost in the pan. If the sytem looks dirty, repeat a few thousand miles later.

The flush can loosen any deposits in the system which may or may not clog passages in the valve body. But - if you drop the pan and the system is clean - the flush would likely do no harm. But if you have sludge in the pan and particulates in the fluid, then it's a good idea to say don't do a flush.

But just to arbitrarily say a flush would ruin the tranny is just an old wive's tale IMHO.
 
I personally think that what perpetuates the "rumor" that a transmission flush causes transmission failure is quite simple. Someone is having issues with their transmission so someone recommends they get a transmission flush and then shortly after the flush their transmission craps out.

Of course I'm sure this doesn't over every instance, but I'm with Driller on this one. Just drop the pan and change the filter. There seems to be much less controversial on if that can harm the transmission.
 
What they used ot teach ius when I was in the business was that when ATF gets very burnt it starts to coat the worn parts with varnis compounds. The worn burnt fluid is also a very poor lubricant and hydraulic fluid. When the new fluid is put in it starts to dissolve the deposits. They loosen and can clog passeges ( as JP states). Also the varishes seal up worn areas that leak internally. When deposits disolves the transmissions starts to lealk intenrally. Possibly leading to severe slipping and even failure. I would not go by the 100,000 mile rule, but if the car has never had it changed then the trans has been severly neglected. Put a sample of the fluid on some white paper to get a good picture of the color. Also smell it. If it smells very burnt (compared to new fluid) it may not be a good idea to change it. Dad may be right. It is a crap shoot. Yu could change it and have no problems at all.
 
beerdog said:
What they used ot teach ius when I was in the business was that when ATF gets very burnt it starts to coat the worn parts with varnis compounds. The worn burnt fluid is also a very poor lubricant and hydraulic fluid. When the new fluid is put in it starts to dissolve the deposits. They loosen and can clog passeges ( as JP states). Also the varishes seal up worn areas that leak internally. When deposits disolves the transmissions starts to lealk intenrally. Possibly leading to severe slipping and even failure. I would not go by the 100,000 mile rule, but if the car has never had it changed then the trans has been severly neglected. Put a sample of the fluid on some white paper to get a good picture of the color. Also smell it. If it smells very burnt (compared to new fluid) it may not be a good idea to change it. Dad may be right. It is a crap shoot. Yu could change it and have no problems at all.
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After Johnny Walker, spell check is your friend. ;)
 
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