Clutchless

Add 4 or 6 extra ounces to account for spillage, and fluid that sticks to the sides of the container and mis-measurement etc.
How much did you get on your initial drain? I found that the transmission runs better filled with 2.25 quarts. You can experiment since you are doing multiple drain and fills.

My old Sienna drained 1.8 quarts and did not drive like the RX. When more fluid was added it improved trans function and throttle response from a stop was much better and instantaneous just like the RX. Before it was harder to get moving. I think the lower fluid level affected performance. New fluid also helped shifting speed and smoothness.

Brownd3max

I got about <2 qts. of almost black fluid- so glad I listened to you all on here about doing this now @ 62K miles... Noticed that the plastic splash plate with two screws (that must be removed for filling access) ALSO has a plastic push-pin at the front- how the h*ll do ya re-install that thing? LOL... (BTW- I saw on eBay there's a plethora of sellers w/ comprehensive ATF fill kits for multiple brands, but I think I'll just pass on those.)

RX in NC

I do not remove the plastic push pin from the plastic splash plate. I just remove the metal screws and rotate the splash plate out of the way in order to gain access to the fill plug. Works for me.

Clutchless

I think it has 2 pieces that are pulled apart slightly for it to fit in then it is pushed flush to expand and fill the hole. You can buy generic pins that fit at most big chain auto parts stores or Home Depot or Lowes (in the bolt & screw section, usually in the metal cabinets of specialty stuff) . Just measure and photograph the hole before you go shopping. Or try to fit another bolt or screw and nut in there, or ignore it and just use the other bolts. It does not need to be reattached the same way that Lexus did it.

Brownd3max

OK, Thanks guys, I've got the pin/cover thing handled... Now- I'm in a minor quandary because I've done 3 cold drain/refills so far.(driving a few miles in-between each one for circulating purposes). The ATF is still coming out fairly blackish. Not see-through. I've got enough ATF to do one more drain/fill, which will then total about 8 quarts exchanged. Question- Should I do a FIFTH drain/refill (2 more quarts), or am I beating a dead horse with diminishing returns? Please chime in!

Clutchless

You have done enough and are good to go. Most of the fluid has been replaced after 3 drain and fills.
You should drive it longer before the next drain and fill. Let the new fluid have more time to clean things up and help the transmission before doing another drain and fill. I do initial ones about a week apart.
The fluid will always turn that dark unless you have a complete flush - fluid exchange by machine - performed.
.
Just drive it for now and next oil change do another 5th ? drain and fill.

RX in NC

^^ What he said....