The trans drain and fill on my 2006 RL that was supposed to be a straight forward of draining 3 quarts and adding three quarts is now somehow not so simple.
Before draining, the level on the dipstick read almost 1/2 inch above the top hole on the dipstick with it warmed up and not running. And if I let it run and then check it within 90 seconds it was about 1/4 inch above the top hole.
Well exactly 3 quarts drained out.
I have now only added 2 1/2 quarts which brought it up to the top hole with it warmed up and the engine off.
Should I add more or should the engine be running when I check it?
Thanks

 

Reference the below processes to make your exact determination as to whether more ATF should be added:

ATF Level Check
NOTE: Keep all foreign particles out of the transmission.
1.Warm up the engine to normal operating temperature (the radiator fan comes on).
2.Park the vehicle on level ground, and turn the engine off.
NOTE: Check the fluid level within 60-90 seconds after turning the engine off.
3.Remove the dipstick (yellow loop) (A) from the dipstick tube, and wipe it with a clean cloth.

4.Insert the dipstick into the tube.
5.Remove the dipstick (A) and check the fluid level. It should be between the upper mark (B) and lower mark (C).

6.if the level is below the lower mark, check for fluid leaks at the transmission, hose and line joints. If a problem is found, fix it before filling the transmission. If the level is above the upper mark, drain the ATF to the proper level.
7.If necessary fill the transmission through the dipstick guide pipe opening (A) to bring the fluid level up to the upper mark. Always use Acura ATF DW-1 (ATF Z1 has been replaced by ATF DW-1, Honda Service News Nov 2010) Automatic Transmission Fluid (ATF). Using a non-Acura ATF can affect shift quality,

8.Insert the dipstick back into the dipstick tube.


ATF Replacement
NOTE: Keep all foreign particles out of the transmission.
1.Bring the transmission up to normal operating temperature (the radiator fan comes on).
2.Park the vehicle on level ground, and turn the engine off.
3.Remove the ATF filler bolt and drain plug (A), and drain the automatic transmission fluid (ATF).
NOTE: If a cooler cleaning is used, refer to ATF Cooler Cleaning.

4.Reinstall the drain plug and a new sealing washer (B).
5.Refill the transmission with the recommended fluid through the filler hole (A) to the upper mark on the dipstick. Always use Acura ATF DW-1 (ATF Z1 has been replaced by ATF DW-1, Honda Service News Nov 2010) Automatic Transmission Fluid (ATF). Using a non-Acura ATF can affect shift quality.

6.Install the ATF filler bolt (B) with a new sealing washer (C).

 

Thanks for the response.
I found that the level on the dipstick after 60 seconds is slightly lower if I moved the gearshift through all the gears before turning it off instead of just letting the engine run.
Using this method, I ended up adding back a total of 2 qts 28 oz. with the dipstick level exactly at the top hole.
Four ounces of fluid probably won't make much difference but I like to get things right.

 

It's likely, if you did not perform the last ATF service (?) that the transmission was slightly overfilled, indicating that '...1/2 inch above the top hole....'
As long as the fluid is 'between' or as you currently have it, at the top hole. You are good to go.
Most important things to remember when checking the ATF level is:
1) Get the ATF up to operating temp.
2) Have the car positioned on level ground.
3) Check the level as quick as reasonably possible after engine shutdown.
4) Making sure fluid level is between the ATF dipstick holes, no higher than the top hole.