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Discussion Starter #1
I want to see what the general consensus is these days regarding changing fluid on a high mileage transmission. More specifically a transmission with 60k plus miles and you do not know the history. Let's assume the fluid is original and the vehicle is displaying no driveability issues yet looks dark and worn.

Theories are that if fluid is not changed regularly and mileage increases the clutch material and band tolerances increase with wear. Friction surfaces may harden or crystalize. The suspended contaminates in the old fluid actually act as a friction modifier and help compensate for the wear.

When the unit is flushed out the new detergents clean the surfaces and all that gunk goes into the filter clogging it up. You may or may not have fluid starvation issues and/or the increased tolerances with fresh fluid makes slipping occur which increases heat and accellerates wear further.

I hear people say shops will not change their fluid on high mileage transmissions and/or make them sign a waiver. I've also heard people claim their tranmssion went out just after a fluid change.

I'm not fully convinced. Until today, I've never had an issue nor know anyone with a failure to occur after a fluid change. On my old 2000 Dakota I changed the fluid the 1st time at 90k miles. I also towed a LOT. I changed it again at 175k miles. It was still solid at 220k miles when it went to the CFC program.

This thought came up as my boss just had the transmission rebuilt on his Jeep Liberty. Uses the same 545rfe tranny. It has about 75k miles and was the original fluid. The local Midas shop talked him into a fluid flush. A week later he tells me he dropped it off at a transmission shop because it was slipping and bucking. They of course told him it needed a transmission. I unfortunately didn't get the oportunity to check it myself.

I'm not convinced it was an actual transmission failure. I'm guessing they either used the wrong fluid or short filled it.

Discuss.
 

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I've heard this as well. Went to have my Tranny flushed on my old Durango and the shop told me it was a very bad idea. Fluid changes I dont think are a problem but a flush on a tranny can dislodge crap plugging up the filter and fluid passages. It also depends on if the transmission was serviced regular. Consistent changes and a flush wouldnt be a big problem I think but I'm not an expert.
 

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Just a poor shlep......
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It is hit or miss on a 75k fluid exchange, which is different then a drop the pan, replace the filter, clean up the pan, and reinstall with new fluid. IMO, most of the fluid exchanges are a waste of cash if they are doing it at more then 40k.

Now, I have done multiple high mileage fluid changes due to internal solenoid failures and yet to have anyone of those comeback and bite me in the ass.

Your boss's Liberty probably had Dex III put in and it delaminated the frictions leading to a clogged filter. This then ends up as a slipping condition.

Brian
 

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Discussion Starter #4
Your boss's Liberty probably had Dex III put in and it delaminated the frictions leading to a clogged filter. This then ends up as a slipping condition.
Brian
That's my line of thought too. I'm going to ask him for the receipt and see if it shows ATF+4 or something else.
 

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Yeah, definetly see if the shop tards put the wrong fluid in. The 45RFE is a stout trans and from what I've seen, the bands are what seem to go in most trannies after a high mileage fluid change. This trans has no bands.
 

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Discussion Starter #6
I was asking him earlier if they did a drain/fill or a flush. He said they sold him on the idea of a machine power flush so it would clean the converter, cooler, etc...

I'm betting the flush machine is pre-loaded with Dex and they use it on everything that comes in there. I'm going to stop by there on my way home under the premise I need a quart of trans fluid. Going to see if they have any ATF+4 or if they offer a quart of Dex and tell me it's the same.
 

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I'd steer anyone away from a flush on a high mileage trans. Regular fluid and filter changes are fine.
On earlier non-RFE Dodge tranny's - 42-48 RE/RH, band adjustment is recommended when you do your first fluid change. The front band can be adjusted any time, but you need the pan off to adjust the rear.
 

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Discussion Starter #8
Well we have some closure on the issue. I gave the boss the theories on what happened and he presented the info to the shop that flushed the fluid. Without admitting any fault they agreed to re-imburse him for 50% of his rebuild cost.

I went with him and did notice they are using a flush machine and it appeared to be pre-loaded with 10 to 15 gallons of trans fluid. It had a pair of opaque tanks. One for clean out and the other for dirty in. Probably loaded with Dex as was likely the fluid they used on his trans.

Of course the transmission shop only charged him $1300 to begin with so I'm suspecting they did nothing more than clean it out, maybe a solenoid and/or clutch then slap it back in. No real failure to speak of. I'm thinking it just clogged the filter and lost prime. But in the end he ends up with a rebuilt and warrantied transmission for $650....
 

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I went with him and did notice they are using a flush machine and it appeared to be pre-loaded with 10 to 15 gallons of trans fluid. It had a pair of opaque tanks. One for clean out and the other for dirty in. Probably loaded with Dex as was likely the fluid they used on his trans...
That's exactly why I didn't want to go anywhere but the dealer when I had my trans flushed at 50k.

I'll just be dropping the pan and changing that way from now on...just did it this summer at ~90k and installed a Trans-Go kit.
 

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I also agree with the "drain and refill" idea. Just did mine at 125K just to make sure I didn't have tons of crap in there. I have some cold shifting issues (2-3 shift only all others are fine when cold or warm) but the flush idea scares me.
And yes, I had a 'person' tell me Dextron was fine. Glad I read this site because I knew the +4 was correct.
 

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If you develop problems after a tranny flush, no matter what the mileage, then either your tranny was already going bad and you just didn't know it yet, or as mentioned above they used the wrong fluid. I've never considered that shops may use the wrong fluid during flushes before, but after this thread it makes a hell of a lot of sense.
 

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I would also bet that they used the wrong fluid. I worked at a lube shop back when I was 18, our manager was a real mechanic, so he knew what the different trans used. I worked at one of the other stores for few days, and they did not have a clue or a care what went in what, they had a barrel of atf and thats what went in everything. You have to be careful, the training in some of the chain stores is a joke. The trans shop that did my brothers neon a few weeks back, flushed it, then dropped the pan and did the filter, then topped it off, at 130000 miles it shifts like a new trans. I was always of the opinion that if it breaks after a flush it was going out already.
 

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I'm of the opinion that unless you use a vehicle that specifies Dexron II or III, then doing a transmission flush is akin to playing russian roulette with a clip-fed weapon. Unless of course you're flushing it yourself with the cooler lines into a big tub and have handy several gallons of the proper fluid in your own driveway.

Our Durango will get a pan drop and filter. The Valvoline LOF place said, "sure we'll drop the pan and change the filter but we'll do the flush, too, and you have to sign an agreement because you have 19x,000 miles."

I replied, "then you are not touching this transmission unless you sign an agreement that states your flush machine isn't coming within twenty feet of this truck. And after you drop the pan, change the filter, adjust the bands, put the pan back on with a new gasket, you will fill it from the dipstick tube with ATF+4."

"BUT THAT WILL TAKE FOREVER"

"But I'm not handing over $80-$100 for you to ruin this transmission with all the Dexron III in your flushing machine. Bye!"

I have the same problem with my Torino. It takes Type F. And although it is probably WAY more tolerant of Dexron, I'm not taking any chances.
 

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My opinion.... bite the bullet and get it changed at the dealer. They'll drop the pan, flush it, change the filters, adjust the bands, then fill it with ATF+4. I think when I had mine done, I only paid $100 for it and an oil change. Well worth it!
 
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