I just sucked all 2 gallons of engine oil from my engine with a hand-pump vacuum oil sucking device. The tube is small enough to fit all the way into the dipstick and touch the bottom of the pan. The whole process took about 4 minutes (including dumping the reservoir on the oil sucker because it only holds 1 gallon).

You could buy one of these handy little devices and suck as little or as much oil as you desire. All 2 gallons for a change, or a few ounces for an analysis, and be done in a matter of minutes.