Bill:

You are correct in that the oil drain plug is on the side, not in the center.

But it is also true that the bottom of the oil pan is sloped towards that drain plug (just inspect it and you will see), and thus when one opens that plug with the oil hot, ALL of it comes out. It also helps to wait about 10-20 minutes after shutting off the engine, to allow drainage of oil from above to the bottom of the pan......Andras