SR-71

heard its not a good idea to do flush on a high mileage (over 150K) 09 acura tl sh

justnspace

iTrader: (1)

generally; when the term "flushed" is used...it's referring to a machine to "flush" the old fluid out...this pressure can break things.
it's better to do a drain and fill.

the tranny will only drain 3 quarts at a time, due to the clutch packs holding fluid.
it is advisable to do a drain and fill 3 times to fully change out the fluid...
3x3x3...3 quarts drained, 3 quarts filled, 3 times

horseshoez

iTrader: (2)

As Justin correctly pointed out, doing what is typically referred to as a "flush" is bad for automatic transmissions, regardless of mileage. Just following the drain/fill recommendations in your Owner's Manual, and if you're worried about the condition of the remaining ATF, then do as Justin suggested (i.e. do the drain and fill routine three times over a period of a few days or weeks).

hometheaterman

Yep, as these guys said, don't do a flush. Just do a drain and refill as the manual states.