closeanuf said:
I would not recommend the transmission flush. I would simply drain and refill and replace the transmission filter. From what I have heard about flushes they force fluid thru the transmission and knock things loose.
That is not true if they get flushed as I have always seen it done.
(Not the part about a flush sometimes coming shortly before a failure...I mean about "knocking things loose" being the cause.)
ATF, even dinosaur rendered ATF is highly detergent. There aren't deposits inside transmissions like engines produce.
Flushing an aged engine is a risk. Especially if it has been on dino oil with few changes. Not so with a transmission.
The fact is, if your trans fails after a flush, it was going to fail anyway.
You may find a few doing this (the ones I have seen torn down post "flush/failure" had obvious catastrophic wear issues and were compromised long before the fluid got changed) but it very rarely happens. I was told by the transmission guy, "if the ATF had lubricity like new ATF, it would not have worked. The new fluid was not loaded with particles of clutch material...and so post-flush, it could slip.
All a flush usually consists of is feeding new fluid into a cooler line till the return turns new color. That's it. (That is all I have ever done...the guys in two of the fleet shops said the same. There are no pressures involved that the vehicle does not make all on its own.)
To each his own but keeping old fluid in there because you are afraid of being jinxed by replacing burnt/contaminated fluid with new?? Not logical if you understand how they work. Your best bet is new fluid, not less than half of the old stuff left in the unit.
BTW, you risk getting grit inside the valve body more by dropping that pan than leaving it alone. Even a 15MPH wind can put granules in a valve body that can screw things up.
(Fuel pumps seem to let go right after a fill up, too.)