My best resource is a couple of good friends who have owned trans rebuild businesses for many years.

When I asked the same question, the primary answer was clean/new fluid is better than old, period.

Other information flowed also: All seem to agree that the "flush" process used at many quick-lube places has disaster potential, all said that they would never have a transmission "flushed".

I was also told "don't shock the system". Basically if the fluid looks and smells good, drop the pan and change fluid/filter, a couple of times, rather than the whole enchilada at once, leave the torque-converter alone. I was told that there was some risk of "dry-starting" the torque-converter and damaging the seals after draining-refilling.

Different fluids have different properties, one being how much they swell seals, changing drastically in an old transmission could cause internal leaks which means that you might lose control pressures and not shift properly (or at all). Thus the "don't shock the system" by changing drastically the type of fluid.

I had the pan dropped and its fluid/filter done by a local shop, M1 added.

After about 2,000miles, I wanted to have it changed again, noticed the trans-drain plug was about 1-1/2 turn from seated, ... decided to do it myself next time.

Throwing caution to the wind, drained/dropped the pan, drained the torque-converter, changed to M1 syn stuff. That was about 4,000miles ago, no problems. I refilled immediately after draining the torque-converter and re-fitting the pan & new filter, a little spooked by that dry-start thing, probably more likely if left overnight or something.

Was cautioned to never use paper towels, even for checking level, so used good clean shop rags.

Change the fluid and filter, clean is always good.

"When I asked the same question, the primary answer was clean/new fluid is better than old, period." Babymog

Well, that sorta seems obvious...but I am glad they came up with the right answer...

"Other information flowed also: All seem to agree that the "flush" process used at many quick-lube places has disaster potential, all said that they would never have a transmission "flushed"."

There has been much discussion about quick lube type places...my father had a drain plug fall out 10 miles after they changed the oil... So I would never have anything done by one of those places.... particularly to cars as old as ours... but that is different than saying a careful owner , after he had neglected to follow the service interval...or on a car new to them should never be flushed... there is good info in the archives about trans-x... It is not a miracle fluid... it is just a varnish dissolver... and varnish can clog the small holes necessary to apply the hydraulic pistons which activate the clutches in an auto transmission... and it also has rubber swelling properties to help stop some leaks...
It is unfortunate that Changing to Synthetic has been mixed into this thread... it mixes up two very different questions...

"Change the fluid and filter, clean is always good."
True... but just doing that may not be enough to take out years of built up varnish.....
Again, I suggest you read in the archives about trans-x... lots of good information there...

I change all of the fluids on used cars when I buy them, unless there is written proof (receipt) showing when it was done. Even then I tend to change the fluid in question out sooner rather than later.

Just because I am paranoid doesn't mean they are not out to get me...

In this case the fluids in the car.

Matt L, since you are doing a couple of changes in fairly quick order have you though about trying the "leave it idling in reverse agaist the garage wall trick"? It is a trick that works well for a specific transmission type over on the Saturn threads. 80% of the time it solves one of the typical problems with their automatic transmissions. The idea being that it causes the passages for the reverse gear to get a good strong flush with fresh fluid. It is on the shouldn't hurt list for me. Let's face it we spend lots of time in the other gears, not a heck of a lot in reverse.

Cheap tranny fix?

There is a link from there to the Saturn forums.

-Jim

__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

The documents for my model say to change the fluid and filter every 30,000 miles.

-Jim

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__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.

While I agree that it wouldn't hurt, I'm not having any trouble with my transmission. I think I'll just run it normally between the fluid changes. All of this will have to wait until the middle of November anyway, as I'm only able to drive the car about 10 miles a week until then.

The instructions on the Trans-X can say to run the car at a high idle and cycle the gear shift lever between each gear.... while using the brake.
If you think of the physics involved... there is no difference to the transmission between using the brake and being pressed against a garage door....

DOOR!!!

I said wall, not door!

-Jim

__________________
1995 S350D, Green with black leather interior.
Bought January 2008 w/ 233,xxx miles.
I did 22,000 miles during the first year of ownership.