trans fluid change and your opinion - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 8 (permalink) Old 01-04-2007, 07:05 AM Thread Starter
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trans fluid change and your opinion

ok guys i have this itch telling me to go ahead and change the fluid in my 97 auto trans now i would have to dig up the papers from the previous owner but at MOST the last fluid change was 40k ago (i know this cause thats when the new trans was installed, and very posible that it has been changed a time or two since then.... anyways i told my cousin that i want to change it and he said "ABSOLUTLY NOT" "thats the worst thing you can do to an older truck" he says that if i change the fluid the detergents in the new fluid will break down the buildup and clogg the lines and valves in the trans and destroy it, he also went on to say that he will never change the fluid in anything he owns or ever will own. i proceded to call him an idiot but i figured what would it hurt to get your opinions on this.
i can understand it if the truck had 150k on the original fluid but at most i have 40 and like i said probably much less, my consern is for the longetivity of my trans i read all the service notes the previous owner gave me and there were a bunch n there that were oil changes and the tech wrote something reminding him to change the trans fluid every 15k i saw it numerous times and then bam there is a trans replacement at 123k please give me your advice on this FYI i bought it with 150k and it now has 164K only thing i have done is drain the water seperator and oil changes. thanks, chris
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post #2 of 8 (permalink) Old 01-04-2007, 01:21 PM
 
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Old wives tail. Same story has been around in engines since detergent oils first came out. Trannys don't have combustion inside so none of the harmful by products form sludge like an engine will. Fine particles of clutch, bushing, and thrust materials as they wear is all. Black varnish buildup litely coats parts from the detergents in ATF suspending the above. Fresh additives are good for seals. Change it. If changing fluid kills it...It didn't have long to live anyway.
He may get a few more miles from an engine that way. One that will have wear on every part including valve guides and the cylinder bores. Sludged engines are expensive to rebuild. :
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post #3 of 8 (permalink) Old 01-04-2007, 01:52 PM
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Quote:
Originally Posted by just visiting
ok guys i have this itch telling me to go ahead and change the fluid in my 97 auto trans now i would have to dig up the papers from the previous owner but at MOST the last fluid change was 40k ago (i know this cause thats when the new trans was installed, and very posible that it has been changed a time or two since then.... anyways i told my cousin that i want to change it and he said "ABSOLUTLY NOT" "thats the worst thing you can do to an older truck" he says that if i change the fluid the detergents in the new fluid will break down the buildup and clogg the lines and valves in the trans and destroy it, he also went on to say that he will never change the fluid in anything he owns or ever will own. i proceded to call him an idiot but i figured what would it hurt to get your opinions on this.
i can understand it if the truck had 150k on the original fluid but at most i have 40 and like i said probably much less, my consern is for the longetivity of my trans i read all the service notes the previous owner gave me and there were a bunch n there that were oil changes and the tech wrote something reminding him to change the trans fluid every 15k i saw it numerous times and then bam there is a trans replacement at 123k please give me your advice on this FYI i bought it with 150k and it now has 164K only thing i have done is drain the water seperator and oil changes. thanks, chris
You told him right.

If you want to change it go right ahead. I typically make 100,000 miles the max change interval for cars and light tucks, but with the torque these trucks have and especially if you were towing 50 to 60,000 is probably a better change interval.

I agree that if your trans goes after a fluid change it was going to go no matter what.

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post #4 of 8 (permalink) Old 01-04-2007, 10:54 PM
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It depnds on the ATF condition

If you PULL with your car/truck, then the 100,000 mile "ok to change window" does not apply, and for many vehicles the "safe" uppre range is much closer to 70,000 miles in "normal" service.

ATF contains calsium, with increased HEAT (the biggy) and age more an more calsium is absorbed by the friction elements (clutch pack), this makes the ATF VERY grippy. Since all modern electronic transmissions have "adaptive shifting", the PCM DECREASES line pressure to keep the factory shift feel with the grippy old/burned ATF.

When you change old or burned ATF the friction elements have much more calsium build-up than normal, and the new ATF has a fresh supply of it as well. Combined with low line pressures, this makes the shifts SLOW and allows a LOT of slippage, even if for a short time while the friction elements fully engage. This will severely overheat the ATF, and if left alone can KILL the seals and friction elements in a few hundred miles.

You are completely safe to change your ATF at this point, just as if it were a new vehicle.

You SHOULD remove ANY "filter" that may have been installed to catch particles from the old trans, AND replace the cooler(s) in the radiator and external. This will ensure no damage is done to the trans by metal particles in the cooler circuit.

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post #5 of 8 (permalink) Old 01-04-2007, 11:36 PM
 
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What does break a bunch of crap loose if it has been a while since last change, is those "chemical flushes".

Stay away from that crap, do a DIY trans flush and get that stuff changed!

Good clean fluid never hurt anything.
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post #6 of 8 (permalink) Old 01-05-2007, 06:49 AM Thread Starter
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ok guys guess that is a 100% go couple more while i am at it you guys say 50-100k intervals... any idea why the service place told my previous owner "every 15k??? oh and another thing.... i ws thinking about having a place that can power flush it to make sure i get all the nasty out... loco motion is this what your saying to stay away from?

whats the best fluid to use i dont care to get the expensive stuff if its only going to get changed every 50-100k

and this may sound stupid but this is my first auto so all my previous vehicles were just like draining the motor oil is there anything different as far as doing it in an auto? thanks for the time and help!
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post #7 of 8 (permalink) Old 01-05-2007, 07:49 AM
 
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We may have said it doesn't hurt to change it after 50-100K.
The recommended interval is 30,000 miles.

The service shop told you 15K cause that's how they butter their bread.
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post #8 of 8 (permalink) Old 01-05-2007, 03:52 PM Thread Starter
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Quote:
Originally Posted by LocoMotion
We may have said it doesn't hurt to change it after 50-100K.
The recommended interval is 30,000 miles.

The service shop told you 15K cause that's how they butter their bread.

possible or now that i think of it the previous owner would not even put the key in the ignition unless he had his skid steer loaded and hooked up. and on top of that he towed it to colorado, california, montana, and nevada a LOT, it was basically a 100% highway driven truck but it was ALWAYS towing 10-12k so maybe the service thought it would be best to do it sooner,

anyways anyone about changing that fluid?
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