Our test group included five electrically powered pumps and four manuals. From left to right: The Airpower Topsider, the Jabsco Porta-Quick, ShurFlo Flex Vane, the Jabsco 17800-200, the Tempo Oil Boy, the West Marine Oil Vac, and the Airpower Marina Pro (foreground). Not pictured is the X-Change-R.

We don't know of many people who change their own car engine oil these days. With Jiffy Lubes on every corner, and the hassle of properly disposing of used oil, it's no wonder everyone hands off this messy job.

But such convenient and inexpensive maintenance service is not so available to boatowners. Changing the oil on a typical diesel or gas-powered auxiliary engine is a royal pain in the neck, and if you have to hire someone else to come and do it, it's a pain in the wallet. Everything is more expensive when it comes to boats—we all know this. That's why gadgets like the portable oil changer can be…