I bought the following oil changer:

http://www.wholesalemarine.com/pc/PE...+Capacity.html

and used it yesterday to change the oil in my boat and was extremely pleased with the result. See my winterization post for pics of the unit in action.

I inserted it into the oil drain hose instead of the dipstick tube since I am sure that the oil drain hose will position the extractor tube at the lowest point of the oil pan. After about a dozen pumps, the oil started to flow through the tube. I pumped it a few more times until I could feel positive resistance on the pump handle. I pumped it 3 - 5 more times every few minutes to ensure positive suction continued. It took less than 10 minutes to get all 5 quarts out of the crankcase. No leaks, no mess to clean up, worked great. I would highly recommend this oil extractor.

Note that I ran the boat on the river for a good 15 minutes to get the oil nice and hot, then drove it onto the trailer, waited 5 - 10 minutes to let it cool a little, then extracted the oil right there at the boat ramp parking lot.

Al