Change transmission fluid or not?

I have a 92 voyager, 150,000 miles. I have had it for the last 100,000
miles and have never changed the transmission fluid. This is because I have
heard that once it has been let go that the fluid thickens and putting in
new, thinner fluid may cause valves to leak and shifting problems.

Is there any truth to this? Should I change fluid or am I risking
catastrophic failure? I plan to keep the van at least another 50,000 miles.

The transmission works perfectly most of the time but occasionally will get
stuck in second. Turning off the ignition and restarting the engine has
fixed this each time so far.

Joseph Osborne
Carlisle, PA

 

It's advisable to change the transmission fluid and clean the screen every two
years. Supposedly, the best thing to keep from having transmission trouble.
You're way overdue.
Carl

 

My opinion:

If you do not change the fluid AND FILTER, you are going to have a major
problem in the not too distant future. The fact that your vehicle is
already going into "limp mode" (2nd gear) occasionally is a sign of trouble.
If you are lucky it is because the dirty filter is restricting fluid
flow/pressure. I'd do this/get this done ASAP and hope the existing problem
goes away. if it does not, you will have a major expense of
rebuilding/replacing the transmission.

Bob

 

Cnamge it. If it fails it is not because of the new fluid - much more
good done by changing than by not.

 

ABSOLUTELY change it, using the correct fluid and filter.

 

Some recommend against fluid changes in high mile units.
http://www.autoguide.net/tmm/austin25.shtml

 

Some recommend smoking 2 packs of cigarettes a day and only ever eating
McDonalds. You can find all kinds of stupid and wrong advice out there.

The original poster is long overdue for a fluid and filter change. By
changing now, he *may* forestall transmission repair. By failing to do so,
he's headed for an expensive repair.

DS

 

Never heard that one, but it sounds like an old wives tale.

I'd change the oil and filter and probably wouldn't be a bad idea to
have it flushed with a good system such as Wynns.


Matt

 

I'm not a tranny expert or mechanical engineer (I am an engineer, but
electrical), but this is one of the most hokey things I've read. If the
clutches are so badly worn that they are depending on junk in the oil to
function, the likely other parts of the transmission such as the oil
pump and bushings and bearings are also shot and the dirty oil is just
accelerating their demise. I'd change the oil and if the tranny stops
working then it was due for mechanical repair anyway. Leaving
contaminated fluid in it only ensures a catastrophic failure in the
future, probably in the middle of nowhwere, at night, in a thunderstorm.
You make the call, as the IBM commercials used to say.


Matt

 

Just my opinion, but that's urban legend nonsense. Even if the unit
fails because it was somehow magically being held together by sludgy
fluid then you're better off KNOWING that it was shot rather than
stranded somewhere.

 

My Father once had a 1963 Plymouth Valiant, which he bought when it
was 5 years old, with 93,000 miles on it. At about 110,000 miles, we
decided to change the fluid. The transmission was working fine at the
time. About ten days later, the transmission experienced a major leak
while driving home from work on the freeway. A rebuilt transmission
was installed.

We were left to wonder if the same problem would have occured if the
fluid had not been changed. Without knowing the car's history, we
could only guess that the fluid had never been changed. In those days,
the owner's manual did not specify a change interval for cars in
*regular* service. I am for changing the fluid on a regular basis, but
can fully appreciate Joseph's concern.

-Kirk Matheson

 

Probably not, but this "major leak" was probably not the result of
changing the fluid, per se. It also probably did not fatally damage the
transmission -- it sounds like your father was the victim of a
less-than-competent and/or less-than-honest mechanic. Transmission fluid
changes themselves do not (cannot) cause sudden catastrophic external
fluid leaks, and sudden catastrophic loss of automatic transmission fluid
does NOT cause the rapid destruction of the transmission as does sudden
catastrophic loss of engine oil.

1963 was the last year for the external trans fluid filter P/N 2400124 on
Chrysler products. It was clamped to the driver's side
engine-to-transmission bracket of your Slant-6 engine, and the
transmission fluid lines were threaded into the filter with a male 3/8"
IV-flare fitting on the upstream side and a female 3/8" IV-flare fitting
on the downstream side. Such is the alignment of the hard lines that it
is VERY easy to cross-thread these connections without realizing it.

Assuming no plain old stupid error was made, such as leaving the
transmission pan drain plug loose or overly tightening it -- 1963 was also
the last year for a factory-installed pan drain, or leaving the torque
converter drain plug loose or overly tightening it -- 1977 was the last
year for torque converter drains -- then the most likely cause of your
sudden serious leak was an improperly connected external trans filter.

It's almost certain your father's car did not require a rebuilt
transmission.

Yes, actually, it did. 1964 was the first year transmission fluid was
designated a "lifetime" item for vehicles in "regular" service. In 1963,
the change interval was still a 3/36 or 2/24 item, depending on whether
the vehicle was in "regular" or "severe" service, and this was stated in
the owner's manual.

DS

 

Depends on where the leak was. If it was at the pan gasket, then, yes,
this IS a case where the oil change was a contributing factor ... but
ONLY because the mechanic didn't replace the pan properly! However,
that isn't the fault of the fresh fluid or the new filter.


Matt

 

And no doubt that change had more to do with marketing than with any
engineering change.

Ted

 

Yeah, the only engineering change for '64 was the replacement of the
in-pan screen/in-line filter with an in-pan Dacron filter of the type with
which we're all now so familiar.

 

agreed