The myth about changing and not changing transmission fluid

[manaswee]

Mine is 89 Cherokee Laredo, 4 cylinder, 2.5 litre. The odometer now reads 250,000 Both the motor and transmission are in perfect running condition. The transmission itself remains forceful, smooth shifting, no slipping nor jerking. The last time I replaced the fluid (with DexronII) and filter was at 70,000. The fluid in it, is now 180,000 old. At a point in time in the past I had wanted to change my transmission fluid, but I had heard so much about the benefit of "leaving it in there to age for better pressure." After kicking around for some while, I simply forgot the whole idea. "Neglected" is a better word. The urge to replace the fluid does come back from time to time., and the thread by Fredjacksonsan in the recent topic entitled " new 4x4ing" makes me realize even more how important it is to have clean fluid in all the ducts and chambers within the transmission ( I have never really seen the inside but just imagine it).
Is it too late to think of it now? Does the myth of "leaving it alone" hold the true benefit?

[wrightz28]

Originally Posted by manaswee

Does the myth of "leaving it alone" hold the true benefit?

Not a myth. What happens is, yes, it may shift fine and well now with the old fluid. That's because the friction material that was once on disks in the clutch packs is in the old fluid. When the old fluid is removed, so is the friction material.

[javatrooper]

I just change the fluid in mine yesterday. Don't know when it was changes last, 217,000 on it. Not too dirty and shifts fine. The one thing I've heard everywhere is to NEVER have your tranny professionally flushed. Even on newer cars. Often leads to problems. Just a regular fluid change is good enough.

[manaswee]

I would like to thank Wrightz 28 and Javatrooper for the good inputs. I certainly would understand the nature of the outcome whether I finally decide to do fluid change or totally refrain from it.

[javatrooper]

Forgot to mention that I always throw in a can of transX or similar formula to recondition the seals. Just factor in the volume/ounces before adding the ATF. Plus, I always measure the ATF that I drain to get a good idea on how much to add.

[fredjacksonsan]

Changing fluid every 30k, never a problem, in either my 00 or 04. With 250k, not a good idea to flush, though a fluid change isn't a bad idea.

[2000izusu]

Originally Posted by fredjacksonsan

Changing fluid every 30k, never a problem, in either my 00 or 04. With 250k, not a good idea to flush, though a fluid change isn't a bad idea.

i agree

[fredjacksonsan]

Let us know if you're planning on changing it....and at the very least, a filter change wouldn't hurt.

[manaswee]

Yes, I am planning on making the fluid change. The filter will be replaced at the same time as suggested ; the pan will have fresh gasket. I am still somewhat apprehensive about the loss of friction material (the unintended by-product of laziness) which may impair the effectiveness of the clutch pack. I will keep you all posted. Right now, I have my big old heavy duty plastic pan ready. I just need to screw up some more courage!

[fredjacksonsan]

Loss of friction material is what happens - transmissions eventually wear out. My opinion is that they're designed to work on fresh fluid, so I try to keep mine that way.

It's not a tough job, just dirty if you spill the trans fluid on yourself. I've always had good luck dropping the front side of the pan first, it just seems less messy that way.

Let us know if you need some tips, or how it went.

[Scrapper]

i agree it's a myth you should keep on chainging fluid and filter as you been doing.

[manaswee]

Thanks for the support. The Jeep is high enough I don"t even have to lift up to get to the transmission bottom pan. It's been a long while since I did it the first time(somewhere around 1995 or about 15 years ago). This particular unit of mine has a drain plug on the pan. The last time I changed the fluid, I probably drained as much as I could through the drain plug before loosening up all the 10mm. bolts around the pan. I did replace the filter and pan gasket. Also remember that there's a magnet strip on the inside of the pan. I worked to a great length in removing as much as possible the metal shavings that's stuck on it. The owner's manual calls for Dexron II . The last time I had a leak from the cooling hose, I used Dex/Merc to refill. I will probably end up with the same fluid this time, with the addition of TransX to revitalize the seals as a choice recommended by Javatrooper. To Fredjacksonsan, I don't mind getting dirty. It's fun. When I am in the middle of fixing something, I just go for the action and forget about things on the side. If I get stuck for lack of more ideas, I will holler. Again, thanks to all.

[manaswee]

I have done the fluid and filter change for the Cherokee. Superficially when checked with the dipstick, the color of the old fluid did not look so bad, but the big bulk that came out through the drain hole to the waste fluid container, looked worse than I initially expected. It was almost pitch black. I was surprised to find no metal shavings on the two pieces of flat magnet about 1/8" x 3/4" x l" in size. See, one's memory fades with time. As much as I thought I remembered vividly there 's a "magnet strip" on the inside of the pan, there really were two pieces of flat rectangular things put separately in two separate recessed pan bottom. Upon the first fluid change about l5 years ago (75,000), I found so much metal shavings on and around the magnets, but upon this second time (250,000) there seemed to be none. Minute metal particles, if any, are not at all conspicuous. There's a drain plug on the pan. The job was a little awkward but not messy. I did the job lying under the Jeep without lifting it up. From the information I got from AutoZone, this is AW-4 transmission. Fluid capacity for regular fluid change is 4.2 quarts. I filled in around 4.5 to 5 to get to the right level. I might have slightly overfilled. Will have to double-check tomorrow. Full capacity is over 8, but we cannot do a complete change without flushing, I guess.

Just as Fredjacksonsan stated " the transmission is designed to run with fresh fluid," which was the reason that prompted me to decide to do the fluid and filter change, either I do something now to nourish it with my own hand, or wait, wait and wait until the damage is done "by the hand of time!"

After the fluid change, the test runs by several family members and myself proved to be as good as before if not better. One thing is sure: the fluid and filter are new! The myth is also behind me!

[wrightz28]

Well, I'm glad it went well. I guess I'll need to do some studying up on Chrysler (used)transmissions. Dealing with GM and Ford for the majority of my 20 years wrenching, changing fluid in excess of 100k is a risky gamble.

Myself included, had a Buick Lesabre that I had bought with 132K on the clock and not the best looking fluid when checked, but the wife needed a grocery getter. We kept it for a few months til we found her something better. When we sold the car, I sold it to a kid a local the oil lube with maybe 8k added miles. Told him as I do in all honesty everything I know about the car. Pulled the stick and showed him, "I wouldn't mess with this if I were you". Kids is kids, he didn't listen. My wife who worked next door to his shop saw him a few weeks later and asked hwo the car was. Grudginly, his only reply, "it's a lawn ornament needing a $1200 tranmission.

I took the gamble once myself and it bought me time. I bought a Park Avenue for next to nothing. Kid overheated the motor, MANY times and fed it a weekly diet of Barzleak (if you ever want to know what that stuff does to the inside of a motor, it aiin't pretty). So I rebuilt the motor and as being a auto trans with the cooling lines passin gthrough the same taosty radiator as the engine coolant, decided to take the gamble and change the trans fluid out.

If memory serves, the car only had about 75k on it at purchase. The fluid as I suspected was burnt worse than when the wife forgets to turn off the coffee pot in the morning. Suffece it to say, I got a good life out of the trans for about another 65k until it required me to give it a complete rebuild.

So, this raises my curiousity. We bought our 98 with 166k on the clock and the original trans and no service history. Shifts fine (hard at times actually) and fluid looks good. But with us potentially moving to a extremely rural area in a few months with a baby on the way, I'm getting nervous about it's life expectancy.

Keep us posted on how it goes for ya.

[manaswee]

Wrightz28, thank you for sharing your knowledge, professional and personal experiences. I have read about the pros and cons of doing fluid change at different stages of transmission's life. It may be paradoxical but true that a fluid change for aged and ill-maintained transmission tends to cause clutch failure. I have read somewhere about it happening within two weeks or two months after fluid change as a general estimate. Question remains: Will my transmission of 250k survive the new fluid?

Will let you know how things go.