[onewhippedpuppy]

Originally Posted by Noah930

I'd listen to whatever advice Fred gives, as he's the professional wrench. But the two Hondas I've had hold about 7 or 8 quarts of ATF, yet can only drain a little over 3 at a time. So to be anal about it, the procedure (short of a flush) is to drain-and-fill, drive around 15 minutes at least, and then repeat. Takes about 3 or 4 cycles to get fairly clean fluid. I mucked through the calculations, once, and it's something like 81% fresh fluid after 3 cycles, and 90-something after 4. The alternative to doing it like this all at once is to do just the 3 quarts every oil change or two. Both Honda products we've had have been known to have less than robust transmissions (though we've never had problems), so I erred on the side of more aggressive maintenance.

My approach with my wife's Nissan Quest minivan is to do the drain and fill at every other oil change. You can drain about 60% of the fluid capacity, so if you repeat the cycle a few times you'll have almost entirely fresh fluid.