Engines, drives, gear cases, generators — gee whiz, boaters have lots of lubricant that needs changing. The right pump makes the job easier. Which is best for you? Review these guidelines before you buy.
A self-priming design is worth paying more for in any marine oil-change pump.
Many, but not all, engines utilize NPT ("garden hose"). Others don't. Consider your thread type.
If you drain oil via the dipstick tube, look for a pump with the largest-diameter suction wand that will fit the dipstick tube's inside diameter.