91RSLT1

My friend wants me to make a post asking if his orginal tranmission will be harmed by doing a fluid and filter change. He has hearded that it can quicken the failure of the transmission. "They" (who ever they are) say the trans. become accustomed to the old fluid, and since it has never been changed and has 80,000, sets up the equation for premature failure or problems. I have changed mine about 17,000 miles ago and plan on doing it again this summer, but that did not convince him. He is going to do new fluid, filter, gasket, and a transmission cooler. I told him don't worry about it, and it can do nothing but prolong and help the operation of his transmission. I dont buy it. What do you guys think?

Z28SORR

"They", don't know that they're talking about. There is NO truth to this.

High mileage transmissions fail more often that low mileage transmissions. So if you wait until the trans. has 80, 90, or 100,000 miles before you change the fluid there are bound to be some that will fail shortly there after.

Changing the fluid and filter can only help prolong the trans. life, period.

P.S. You wouldn't recommend that you leave the oil and filter in your engine for a 100,000 miles, because the engine has gotten used to it.

91RSLT1

That is exactly what I told him and I agree it can only help. Oh and no I would not leave the oil in the motor. Anyone else, just so I can show him and prove my point. Anyone with a different oppion?

TraceZ

<cricket chirp>
<cricket chirp>
<cricket chirp>

Red96Lt1

My friends tranny faild because he changed his fluid at 140K and it had never been changed before. I would at least listen to "they"

2MCHPSI

There is plenty of truth to it. i used to see it first hand all of the time at the various places I worked. The one Gm dealership i worked at for 7 years even had a policy of not selling trans services on transmissions over 100k that did not have serivce history, or proof it has been previously serviced.

The reason being tiny particles of clutch material ect are in the old fliud. These tiny particles actually help the clutch grab. It also help promote even more wear at the same time, creating a weakened clutch and more particles in the trans fliud. you change this fliud with clean fluid and then there is no help in the already worn clutch to grab and it slips with 50 to 100 miles after service.. The customer claims the shop must have performed the maintenance wrong and demands a new transmission.. This happened so frequently when servicing high mileage transmissions with no history of maintenance, that the dealer made a policy restricing anyone from servicing a trans like mentioned.

This probally does not apply to the newer models, since they have new clutch material/fluids that do not even need servicing up to 100k.

But thsi is surely not BS.. I can't even count how many tmes I have seen this happen.

But on that note, 80k might be ok if the car was not constantly raged on and never had a trans service.. After 100k with no srvice history would I normally get a little concerned. If the tranny has history of service, I do not see a problem with it

91RSLT1

This probally does not apply to the newer models, since they have new clutch material/fluids that do not even need servicing up to 100k.

But this is surely not BS.. I can't even count how many tmes I have seen this happen.

But on that note, 80k might be ok if the car was not constantly raged on and never had a trans service.. After 100k with no srvice history would I normally get a little concerned. If the tranny has history of service, I do not see a problem with it [/B][/QUOTE]

Ok I understand and follow the tiny particles helping the clutchs. What is the recommended serivice interval for the transmission (4l60e) fluid? I thought it was 30,000. My friend is not sure if it was ever changed, and doubts it has been. So at 80,000 mi. should he go ahead and do the cooler,filter, and fluid. What about draining the old fluid into a clean pan, and then re-filling it with a 50:50 mixture of the old and the new? Thanks for the input anyone else?

93transam1234

I would suggest your friend start saving his $$ and take the trans to a shop to be refernished.

I am about to 100K in my car and already have a rebuils "built" trans in my laundry room because i know it wont be long till it goes

91RSLT1

He is saving his $ for a new one, when the time comes. He just wants to maximize the life/ use of the current one. Failue is bound to happen someday, but if that someday can be prolonged (by changing the fluid/filter, or not changing the fluid/filter) then why not do it? If you save up the money then why not run the transmission for another year(s), if it can be maintained through maintenance, or in this case the lack of maintence?
Price of cooler,fluid,filter<<<<<<<<<<<<<<<<<<<Price of trans.
Time to install cooler,fluid, filter<<<<<<<<<<Time to install trans.

2MCHPSI

If it has never been serviced and had had a hard life. I personally would not touch it. Tough call. it is like rolling the dice..

91RSLT1

2MCHPSI thank you for all the great info. You really seem to know your suff and definatly have a good resume. So let me ask you,
-Should he leave it?

-Change the filter only and put the old fluid back in, and top off with new?

-Change the filter and put back in a 50:50 mixture of the old and the new?
The car does see track use made 10-20 passes a year for the past two years, it is a mild bolt-on only car? Keep the info coming that is why we are all here, to learn and figure things out.

speed76demon

changed mine at 95,000 and the car now has 106,000 and the trans is fine.

91RSLT1

Was that the first time you serviced the transmission?

allmotorta

FWIW, when I bought my 91 5.0 GT automatic I changed all the fluids in it immediately...it had 101K miles. Within a few miles, the trans started slipping. It never got bad enough to where I couldn't drive it, but it sure was slipping very bad. The trans was perfect before I changed the fluid. With that said, I would do it again

91RSLT1

Did you mean you would NOT do it again? If it made it slip why would you do it again?