Final thoughts on changing old auto tranny fluid...destroys tranny or not?!?!

[starbuck]

So I've not owned a car with an auto transmission since 1990. My 1974 MGB has the standard 4-speed and was my daily driver for 10 years.

Well I have a 1995 Corvette coupe with the auto OD tranny (yes, I know, auto in a Vette..just not kosher for many)

But, after reading post on this forum for a few weeks now, I realized that I have never changed the auto fluid and filter in the thing! I bought it at 65k miles and it now has 145k miles on it. I've never even checked it until today (though I assume the dealership had the many times I brought it in for oil changes & lube or servicing that I didn't have the capablity or equipment to do myself)

I otherwise maintain the car very well but I just simply forgot that it has an auto tranny...sounds weird, I know, but out of sight, out of mind...

I've read that changing neglected auto tranny fluid and filter will often cause the tranny to fail completely. The story goes that the metal particles and gunk in the fluid actually helps hold a worn tranny together and changing it makes the tranny die.

The Transmission shifts fine, engages like it should and there is no problem with it.
The fluid looks absolutely perfect, isn't cloudy or dirty and it doesn't smell burned at all.
So what is the final say on this question?

Is it a wives' tale or is it reality?

Will changing old very old tranny fluid and filter cause a transmission failure or is it more of an urban legend. Mechanics I've talked to come down on this issue around 50-50.

 

[Rodney Gold]

There is no way that servicing a tranny with burnt oil and clogged filters will destroy it - the bad oil and bad filters will....the most important thing to check is the fluid level , too low or overfilled will cause issues. Gunk and metal particles will mess with valves and line pressures and wear clutches and bands etc - definately wont hold the thing together.
Why would you want to fiddle with the tranny anyway if it ain't broke and is doing what it should?

 

[Victory Red C6]

Would you drive that many miles without changing the oil in your engine? My guess is no, so why would you abuse the transmission.

 

[toptechx6]

It is a fairy tale in my opinion, perpetuated because usually what prompts an owner to finally change the transmission fluid is a symptom of some sort (delay into gear, shifts don't feel right etc.) At that point failure is likely inevitable, they change the fluid hoping the "bandaid" will fix the bullet wound and the patient dies anyway.

 

[Paul Higg]

I replaced my auto tranny fluid and filter last summer at approx. 94,000. I did it just because. It drove better and shifted better after that. Not one particle was found on the magnetic chip detector. I don't know where you heard this but it sounds zany to me. Replacing ANY fluid is recommended. Heck, I replace 50% of my son's 3 gallon fish tank once a week. They thrive.

 

[Ruby Fan]

The idea/logic I heard of was this: I believe these are 'learning' trannys, where the shift is made according to driving habits, as the fluid thickens with age the shift point is compensated so the shift can be made the same way. If you change this to new/clean fluid the shift point would happen sooner because of cleaner fluid, and suppose to damage the tranny at this point because of higher pressure due to clean fluid. I don't know if this is true or how to advise you, but if the fluid is still clean, leave it alone. just a thought.

 

[LT4man]

I would find a repair shop which has an auto transmission fluid recycling machine. They can change ALL the fluid in the trans. Even the fluid in the torque converter.

You then would be good to go!

SAVE THE GOSH DARN !

 

[6 Shooter]

I'd have to agree with this reply...

Would you drive that many miles without changing the oil in your engine? My guess is no, so why would you abuse the transmission.

Later . . . . . .
6 Shooter

 

[G Winter]

The only way changing fluid will damage a transmission is if it has so much varnish in it that the new detergent in the new fluid would cut chunks loose so they lodge in passages and the valve body. I have changed oil and filter in many high mileage transmissions with no problems. Matter of fact I am about to change the oil in a 95 GMC with about 140 k on the transmission. I have no idea when if ever it was changed.

Glenn

 

[Black Bart]

So I've not owned a car with an auto transmission since 1990. My 1974 MGB has the standard 4-speed and was my daily driver for 10 years.

Well I have a 1995 Corvette coupe with the auto OD tranny (yes, I know, auto in a Vette..just not kosher for many)

But, after reading post on this forum for a few weeks now, I realized that I have never changed the auto fluid and filter in the thing! I bought it at 65k miles and it now has 145k miles on it. I've never even checked it until today (though I assume the dealership had the many times I brought it in for oil changes & lube or servicing that I didn't have the capablity or equipment to do myself)

I otherwise maintain the car very well but I just simply forgot that it has an auto tranny...sounds weird, I know, but out of sight, out of mind...

I've read that changing neglected auto tranny fluid and filter will often cause the tranny to fail completely. The story goes that the metal particles and gunk in the fluid actually helps hold a worn tranny together and changing it makes the tranny die.

The Transmission shifts fine, engages like it should and there is no problem with it.
The fluid looks absolutely perfect, isn't cloudy or dirty and it doesn't smell burned at all.
So what is the final say on this question?

Is it a wives' tale or is it reality?

Will changing old very old tranny fluid and filter cause a transmission failure or is it more of an urban legend. Mechanics I've talked to come down on this issue around 50-50.

This is what I hate about the Internet.
All kinds of misinformation floating around.

Change the oil. Do it NOW.

 

[RevMatt]

Be careful of tossing around non-PC terms!

So I've not owned a car with an auto transmission since 1990. My 1974 MGB has the standard 4-speed and was my daily driver for 10 years.

Well I have a 1995 Corvette coupe with the auto OD tranny (yes, I know, auto in a Vette..just not kosher for many)

But, after reading post on this forum for a few weeks now, I realized that I have never changed the auto fluid and filter in the thing! I bought it at 65k miles and it now has 145k miles on it. I've never even checked it until today (though I assume the dealership had the many times I brought it in for oil changes & lube or servicing that I didn't have the capablity or equipment to do myself)

I otherwise maintain the car very well but I just simply forgot that it has an auto tranny...sounds weird, I know, but out of sight, out of mind...

I've read that changing neglected auto tranny fluid and filter will often cause the tranny to fail completely. The story goes that the metal particles and gunk in the fluid actually helps hold a worn tranny together and changing it makes the tranny die.

The Transmission shifts fine, engages like it should and there is no problem with it.
The fluid looks absolutely perfect, isn't cloudy or dirty and it doesn't smell burned at all.
So what is the final say on this question?

Is it a wives' tale or is it reality?

Will changing old very old tranny fluid and filter cause a transmission failure or is it more of an urban legend. Mechanics I've talked to come down on this issue around 50-50.

;squint: "Tranny", here in Northern California, has a totally different set of connotations! If you have your hands all over a "tranny," I would not brag about it!
...sorry, I could not resist!

 

[Hib Halverson]

(snip)
I've read that changing neglected auto tranny fluid and filter will often cause the tranny to fail completely. The story goes that the metal particles and gunk in the fluid actually helps hold a worn tranny together and changing it makes the tranny die.
(snip)

Is it a wives' tale or is it reality?

It's a big load if smelly brown stuff.

That said, with about 80,000 miles on the trans since the last change you need to do more than just change the fluid in the pan and the filter. You need to flush the entire transmission. I'd take it to a trans shop which can flush the torque converter and change the fluid and filter.

 

[Vettefan87]

I did a complete trans flush after I bought my vette 5 years ago. It ran me around 100 bucks but the entire system was flushed out and replaced with new. If you just drop the pan you cant get what is in the converter.

 

[G Winter]

It's a big load if smelly brown stuff.

That said, with about 80,000 miles on the trans since the last change you need to do more than just change the fluid in the pan and the filter. You need to flush the entire transmission. I'd take it to a trans shop which can flush the torque converter and change the fluid and filter.

I have to agree with Hib on this one. The only reason I am not doing it on my truck is that I want to be sure I am not in failure mode first. Once I know I am good to go my truck will get the flush treatment.

Glenn

 

[Rogue]

I have heard and read two sides to this coin.

Doing a total flush on an autobox with many miles and never had the fluids replaced can lead to tranny failure because the flush will agitate and circulate the crap that's in the tranny and clog the passageways and tranny ultimately fails.

Change fluid simply by dropping pan, changing filter and filling with new fluid.

Then some of you guys recommend the flush treatment. But just because it worked for you doesn't mean it will work for someone who has 100k miles on their tranny that has never had its fluid changed.

Which is real or which is fiction?

I would think that after 145k miles, the safest route is to avoid the flush and just do the drop the pan thing. You won't change all the fluid but you won't flush either.

Or, if it ain't broke, don't fix it!

 

[Paul Higg]

Well, I can attest to this. Last summer with 95+ on the speedo I had my Corvette specialist to a complete drain, flush, filter and pan seal change. I noticed a difference in the way it shifts. I haven't had one problem with it yet. It is running like new. I just do not understand how a complete flush with clean fluid and replacing the filter can hurt things. Like I said, I see a real difference.

That's my 2 cents for what its worth.

Paul

 

[Topless_Ruby]

Doing a total flush on an autobox with many miles and never had the fluids replaced can lead to tranny failure because the flush will agitate and circulate the crap that's in the tranny and clog the passageways and tranny ultimately fails.

Change fluid simply by dropping pan, changing filter and filling with new fluid.

Then some of you guys recommend the flush treatment. But just because it worked for you doesn't mean it will work for someone who has 100k miles on their tranny that has never had its fluid changed.

Which is real or which is fiction?

I would think that after 145k miles, the safest route is to avoid the flush and just do the drop the pan thing. You won't change all the fluid but you won't flush either.

Or, if it ain't broke, don't fix it!

This happend to a friend of mine. His Olds had 100M plus when he took it to one of the quick oil change shops, they convinced him he needed a "Transmission Back Flush". A week later his car was being towed to the transmission shop. After several days and many $$$ the mechanic told him that the worst thing you can do is have a high milage transmission back flushed.

 

[Paul Higg]

I don't know what else to say. Other people's experiences may differ from mine?