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Discussion Starter #1 (Edited)
I recently came across a GM TSB 04-06-01-029J / March 2020 advising not to power flush the fluid from any automatic transmission . It has been found to harm the transmission per GM . GM now advises only to drop the pan and then refill as needed to the proper level . I personally never thought it wise to force fluid under pressure through the inner workings of a transmission as that sends sediment everywhere . Even worse IMO is back flushing a radiator sending sediment into the cooling tubes and heater core . Somethings are meant to flow a certain direction , just ask a guy that had a catheter shoved up his $enis .
 

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I am not exactly sure what is referred to when GM says "power flush".

when I do my AT trans fluid I drain the pan, change the filter and refill, then disconnect the return line at the radiator(I have a Hayden cooler) and add a short piece of tubing that goes into a bucket, start the engine and pour more Dex6 down the spout into the trans while watching the oil being dumped into the bucket and when the color changes to the fresh Dex6, I stop the engine and reconnect the cooler line and top off the Dex6 as needed.
 

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I have always favored the kinder, gentler way of drop the pan, change the filter, refill, and ride. I fully realize you are only getting a portion of it, but overall you are improving the body of the fluid. Do it again at another service interval of your choice. I see no need to take the chance.
Red flags popped up in my head years ago when Wynn came out with their "Power Flush", bragging about getting all the old fluid out, and replacing it all with new, pretty trans fluid. Sounded good up until they had a release for you to sign claiming NO FAULT if your vehicle did nothing when dropped off the lift and if the shifter lever didn't do chit no matter which way you slammed it.
Many cases were reported doing just that, nah, I have better things to do.
Sure would be rough if a doctor flushed out your intestines that way, wouldn't it?
 

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Discussion Starter #4
As a person that was part of winning a class action suit against GM I find it amazing that GM would actually admit they could be wrong about something . Better late than never I guess . Glad I never went along with that service advisement , always saw it as a money grab by dealerships and service garages that could screw up a working transmission .
 

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I have had three G.M. transmissions flushed and had problems with every one a few years later.
 

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What exactly is done in one of these "power flush's" ? How is it done? Does GM consider the method I described and use as a power flush?
 

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The only "power" was the transmission pump transfering the fluid. The pump on the machine was to dispose of the old fluid in the machine and refill machine with fresh fluid. Maybe its just not a good thing to replace all the fluid at once. With the "flush" i dont think there was ever a filter change involved either. Another thing is I dont believe its a reverse flush. Its more of a fluid exchange from what i know.
 

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If having all the ATF being fresh is bad then it would also adversely affect new and rebuilt transmissions. I would be more apt to lean towards the root cause being the low level of competence and ability to follow directions being exhibited by those performing the "power flush" at home and for commercial entities, so the safest thing is to advise against it. Adding the Dex6 too quickly, not quickly enough, or letting the engine run too long afterwards and running the trans dry, are detrimental to the health of the transmission. Attention to detail is a lost art these days!
 

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When I went through this the term power flush would I don't believe be correct.....the machine is hooked up to the feed and return lines to the cooler and as the old fluid is pumped out the new fluid is put in the system at the same time.Then after the process is complete the filter is then changed.
 

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Discussion Starter #10
Don't get caught up in the terminology . This isn't like Coke being called either pop or soda . GM has stated that a recommended service procedure can cause the failure of your transmission . For the well being of your vehicle heed their warning . Power , forced , mechanical or whatever you want to label it it's considered bad news for the transmission .
 

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Just stick with the "Tried And True".
Over time, I gradually move up to High Mileage Trans Fluids.
Some times, too much action in that area can be worse than just leaving it alone!
 

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Does this apply to all of the year transmissions for the trucks?
Yes I had three transmissions flushed and had issues with all them a few years later.One was a 1988 silverado, a 1992 buick roadmaster station wagon, and a 1998 pontiac grand am.
 

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Well I decided to heed the warning and not swap all the fluid at one time. I pulled 3 quarts out thru the fill tube and added back 3 quarts of fresh dex6. I will do this one more time before dropping the pan and swapping the filter and fluid in the pan. That should be a much softer impact upon the trans. The fluid was a dark brown color with a slight red tint, the trans did shift smoother with just that minimal 3 quart swap.

Thanks for bringing this up, I would have hated to have hurt the transmission while trying to do good.
 

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Discussion Starter #15
I like your approach to this . In the future adding a drain plug when changing the filter would be a great move .
Drain Plug.jpg
 

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I do plan on adding a drain to the pan when I do the filter.

This is my first automatic trans equipped vehicle in 22 years, I just want it to last,,,,,, I still stomp the floor looking for that darn clutch pedal every now and then, and try to shift with the water bottle in the center console, LOL
 

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Just like Talonx, I have been removing and replacing three quarts through the dipstick tube, however I do it with each engine oil change. I change my engine oil and filter every 4000. I have 190,000 miles on the truck now (2006 I5) and no issues with engine or transmission
 
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