'07 manual states engine capacity at 4 quarts but this is on a bone-dry engine. Replacing oil is 3.5 quarts. I recently did mine and it was right on the money at 3.5.
Just buy 4 quarts and change the oil and put 3 1/2 in. Run the engine until it's hot and then check it again and fill to top of line. Make sure it's on the jiffy stand.
Filled to the top line is asking for oil to be blown out the air cleaner, imho. 3 1/2 is the trick - keep the oil reservoir 1/2 full and that's plenty. Just keep checking it until you're sure it's not using oil.