I'd put 5 quarts in then check the dipstick. The reading that you get should correspond with the capacity figure that you believe, if it does not, further investigation is in order.

As far as the reading going up when the engine is warm, I have some trouble with that.

Every advice I've ever read tells the owner to check the oil when cold, or tells the owner to wait a certain period for the oil to drain down.

Even if motor oil expanded a great deal, the manufacturer would calibrate the dipstick for cold conditions so that;
- the owner would not be injured by hot parts
- consistant temperatures would be used - cold means overnight - what is warm?
- the oil sticks to the dipstick better when it is cold making the level easier to read.

Do not overfill the oil, as at some point, serious damage can result.
--
2 8s & 2 7s 600,000 miles total

The capacity is 6 quarts and .4 quarts stay in the oil cooler
so you only need 5.6 quarts for oil change. I can see how this
might cause the Owners Manual editor to be confused. I wonder
if my 70 series manual has it corrected.

I had 5.5 quarts (+/- a bit) and then add the rest a few hundred
miles later next time I check it.

Are you sure both are in quarts, and one isn't in litres? I usually fill up 6 litres myself.