I've not used the cooler-line method so I don't know precisely how much you'll get, but the only way to get more is to use a fluid exchange machine, or do the cooler-line method multiple times. Unless the fluid is really bad, that shouldn't be necessary.
While the pan is off, install a drain plug. That way you can do a quick drain & fill whenever you change the motor oil.
'03 Mercury Marauder (The Blackbird)
Trilogy Motorsports supercharged #61
Too many mods to list / Driveway Queen
'04 Grand Marquis LS Limited Edition (Spruce Green)
Daily Driver (Thanks, Adam!)
'00 Grand Marquis GS (Silver)
Rotted frame and broken transmission crossmember