Keeping the oil at the FULL mark will indeed increase heat loss through the oil pan, but, because the engine runs as needed to maintain itself within it's desired operating temperature range, this will only make the engine run a little more than it would otherwise and so burn a little more gas. There is no benefit in this.
Per the U.S. owner's manual, the oil capacity at the FULL mark, including filter, is 3.9 U.S quarts (p. 312). At the ADD mark it is 3.9 - 1.6 = 2.3 U.S. quarts (p. 282). Using 3 quarts at an oil change leaves the level almost exactly halfway between ADD and FULL. (In my experience, the small amount of retained oil leaves the level a little above halfway.) If that were not acceptable the design engineers would have put the ADD and FULL marks somewhere else.