Well I had a minor oil leak from overfilling my oil tank. I used to fill with that 5 qt jug from wal-mart. The oil seemed to be making its way past the oil filter. I had a thread a while back that I made about it.
Now I keep an empty 1 quart bottle that I fill up and I pour the rest of the 4 quarts from the wally world jug into the engine. Oil level is right in the middle of minimum and max.
Also a side note, the Haynes manual states that overfilling the oil tank can cause a rear main seal leak, just a heads up.
Regardless, I say be on the safe side and keep it at 4.5 quarts if not a little less. Remember, if the level is between min and max you are good! I think it's common sense to keep the oil between the safe levels, but that's just me, it doesn't need to be filled to the brim.