7 quarts is close enough for me. The amount of oil left in the engine will depend on oil temp and how long you let it drain. I'm not usually in a hurry when I do maintenance on my vehicles. After warming the engine to operating temp I'll let it sit for about 30 minutes. Then I'll pull the drain plug and filter and let it drain for about 20 minutes. Then install the new filter and drain plug and add 7 quarts of PUP.
For the truly anal who might be losing sleep over this, drain the oil and replace the filter in your normal way. After reinstalling the drain plug, add the 7 quarts then start the engine allowing it to circulate the oil. Shut off the engine and check the oil level after allowing enough time for the oil to settle into the sump. If it's above full, drain a little back out until satisfied with the oil level. Measure how much you removed for reference when doing future oil changes. Be consistent with your oil changes in the future or this method will not be as accurate.
Brings back a memory of the 2015 F150 with the 2.7. Takes over 30 minutes to drain. A new car testing magazine that buys there vehicles then keeps them for a year had it serviced, the truck was so new that the dealer tech hadn’t fully let it drain so it had 10 qts in it, instead of 6. Oops. (Edmunds.com)
begin quote from article: “Yes, it's that time again. The oil change reminder flicked on while I was driving our
2015 Ford F-150 and a quick check of the Engine Information screen showed the oil life down to five percent. I was near an auto parts store and a Ford dealership, so I bought the oil at one and a filter at the other and got to work. I didn't have to do this myself, but I was gun-shy after
I did oil change number two myself and discovered that the dealer technician had mistakenly added 10 quarts of oil during oil change number one. Besides, Josh had taken it in for
turbo feed line oil leak some weeks back. That dealer technician topped up the oil after he completed the fix. But did he overfill it like the first guy had? Nope. Everything was A-OK on that front. Six quarts came out like they should.”
End of copied article
And you are supposed to wait 15 minutes prior to even checking the oil:
2015 Ford F-150 Long-Term Road Test
EcoBoost V6 Makes You Wait