This is why I took it elsewhere to get it done. I am aware that there are two chambers to empty. However, even if you do empty those two chambers, you still have a few quarts left in the transmission in the torque converter and other places. The shop basically hooked up a system where they pushed in new fluid as they pulled the old out. I don't recall exactly what the procedure is, but I do know that they replaced more of the fluid than I would have with a simple pan drop.

I've heard that another acceptable method of changing transmission fluid is to buy some extra fluid, disconnect the transmission oil cooler return hose and put it in a bucket, and pour in transmission fluid at the same rate at which its coming out since the pump would be pushing out the old fluid, and keep an eye on the color of the fluid coming out. When it becomes red and more clear, then you know you're done.

IIRC with the 4t65s, if youve waited long to change the fluid a flush is not a good idea. ive heard more than a few times of people with high mile 4t65s that get a flush instead of just fluid/filter change and start having transmission issues shortly after.

The problem with that is that people wait until there are problems to flush it, after which its too late anyway.

The other problem is that some machines they use for flushing transmission fluid pressure feed the fluid back into the system at a rate that'* abnormal, which can cause deposits and crud to build up and get stuck in the valve body or other parts of the transmission and cause other problems. Either way, if you're waiting that long to get your transmission fluid changed, you should be kicking yourself pretty hard for it.

so getting a flush with a "BG" machine that runs off of the pressure your transmission produces normally wont hurt it? (given you didnt wait too long)

Absolutely not. Changing the fluid will not harm anything. If your transmission fails after you get the fluid changed, it was going to fail anyway. As I said, most people don't get it taken in to get the fluid changed until they start having problems. By that time, its too late. You might as well save yourself the $100 and run the old fluid till it dies.

thats why i was asking about a flush, ive never heard anything bad about a fluid change and i agree with you on that. my question is about flushing the system, because thats where i have heard bad stories. a fluid and filter change has always been recommended for any mileage transmission, but i have always been told to avoid flushing a 4t65 if the fluid has been neglected.

I have a friend that uses a machine similar to that for coolant and it made replacing my Dex for new this summer a breeze. Thats @ 5years/48k miles. I'll make sure to find one when I want the tranny fluid done. Sounds like the most logical way of doing it given the 4t80'* design.

Lets put it this way. If the transmission dies some time after the fluid is flushed, it was going to die anyway. I think the whole problem is that there are deposits of crud that you loosen up and it gets stuck in places you don't want it, but that'* all speculation. I too have heard stories, but they're just that; stories, and more often than not from people who know very little about cars.

Here in Florida where the summer temps frequently exceed 100 degrees I consider the conditions under which vehicles operate harsh. I prefer to err on the side of caution and have the transaxle serviced about every 30K miles. I'd much rather spend a few hundred more for service than thousands for a rebuild.

A very good point. The heat will definitely burn up the fluid more quickly. I wouldn't go as far as 30k miles though, since the Dex6 is much more tolerant to heat than Dex3 was, but if you do live in a very warm climate, I would definitely get it changed more often.