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

We know of only two people who change their own car engine oil these days—the mechanic who lives next door and the editor’s thrifty Yankee father. With Jiffy Lubes on every corner, it’s no wonder everyone hands off this messy job.

But such convenient—and inexpensive—maintenance service is not yet available for the powerboat owner. It might cost upwards of $250 for a mobile mechanic to come to a 30-foot express cruiser and change the oil in its twin inboard-outboard engines.

Everything is more expensive when it comes to a boat—we all know this. That’s why gadgets like the portable oil changer can be so valuable to the boat owner. And given the…