Jack, for your 2000 Ody, I could not give you any better details than
nwf snake does in this very thorough thread:
http://www.odyclub.com/forums/14-periodic-maintenance/14375-transmission-drain-fill-picture.html
It even has some good pictures. Draining is fairly simple. The ATF drain plug has a square recess in the bolt head that is exactly 3/8" square...perfect for inserting the end of a 3/8" ratchet. This plug requires 36-ft-lbs. of torque when you reinstall it.
The 17mm hex-head fill plug is on top of the transmission (the 1999-2001 Odys are much easier to refill ATF than our 2002 & 2003 vans).
This thread gives details on draining, refilling & driving....and doing a total of 4 drain-refills (driving in between each one to more around fluid in the torque converter). This is the "complete" change that one accomplishes when directed by the owner's manual at a certain mileage interval, depending on whether you drive under normal or "severe service" conditions.
RinconVTR has a good post where he does just a single drain & refill every 15,000 miles on his much newer Odyssey (4-shaft transmission), and he sent used ATF samples to Blackstone Labs for analysis. Blackstone Labs felt that his single changes to periodically "refresh the additives package" (my wording) was a good idea. From what I read on the lab report he posted, they liked his method (as opposed to waiting 60,000 miles [I think that's the interval for his newer Ody] to do 4 drain-refills). So, I do something similar.
Your tranny, like mine, is the older and somewhat less durable 3-shaft design. I was going 7,500 miles between each oil change, but am stretching that oil change interval to 8,500 miles...I still drain-refill the ATF once each time I drop the engine oil for a change.
For your 2000 tranny, my Honda shop manual says the ATF total capacity is 7.6 quarts. That's the total amount of fluid held in the hydraulic power circuits, cooling lines, torque converter, and drain sump. When you drain the sump, only 3.1 quarts will come out. The reason the manual calls for a total of 4 drain-refills (when done all at once at the service interval) is that it is a means of successively diluting the used fluid by successively introducing fresh, new ATF.
OF