Quote:
Originally Posted by vstech
so, what is the point of gradually changing a quart of fluid at a time?
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Well, do you know any of the history of this AT? I dont. I see a car with 265k, who knows if and when the AT was rebuilt, and a trans that is exhibiting funny shifting and leaks.
I totally agree that a pan drop and everything you mentioned is the right approach for an AT that is a known quantity with some history. I dont know the history with this.
Ill bet you have heard of the shops that wont service high mileage ATs, or people who service their transmissions and then they dont work right. Was there something wrong there before? Likely yes, but too rapid a change can make it worse. Why? New fluid will have a far different characteristic in terms of additization and oxidation level. This means that it will clean, disperse and solvate deposits at a rapid rate, and can innondate the filter and other components.
Noplace am I saying that your approach is not valid. I just wouldnt go that route immediately, especially since with new fluid, any cleaning that will occur will immediately lodge in the filter, and so then you just did the job and just loaded the filter up with all kinds of junk.
Putting a good quantity of fresh fluid in gradually and easily from the dipstick (KISS principle) ensures that it gets in, a good quantity of fresh fluid is blended, it can start to clean and disperse, then load the old filter, and finally after getting a decent amount of new fluid in there, then after some mileage, the pan can be dropped and the job done right.
To me it is just a more secure way to get this done, allowing things to be done gradually and not impacting stuff in too rapid/severe a way. Thats when things get clogged up or too much junk loosened.
Back in the old days (2003-ish?) Larry Bible or someone used to swear by Trans-X, IIRC, as a flush to use if things started getting funny. But there were lots of discussions back then about doing gentle, slow and methodical changes first, and it has always been a sound approach.
The aspects of failure and degradation in an AT are far different than in an MT or an engine, diff, etc.