If you're the guy who changes your own oil, odds are you’ve spilled some into the bilge at least once. A portable transfer pump and a bucket for a waste-oil reservoir are a big help. But nothing beats a permanently installed oil changer that’s plumbed directly into the oil pan — especially for multiengine rigs. Not only can you drain out the old, but you also can reverse the pump direction and refill with fresh, clean oil.
Consult with the engine manufacturer to find an oil-pan fitting that will fit the pan and accept half-inch hose. Run engines till warm, and then drain or vacuum all the existing oil. This is also a good time to change the oil filters.
Position the pump on a convenient bulkhead that will make the straightest, shortest runs to the engines and/or genset. Note: Do not exceed the manufacturer’s maximum total hose lengths from the engine to the pump and the pump to the waste oil/new oil containers. This total length represents the maximum the pump can handle without overworking and burning out the motor.
Mark the position of the four corner mounting holes, and drill and mount the pump to the bulkhead. Use rubber bushings, one under each screw head and one more on the screw between the pump base and the bulkhead. Orient the unit upright no higher than five feet above the oil pan, a typical self-priming height for these pumps.
Run hoses from the oil pans to the installed pump. Use a backup wrench to hold the valves from rotating when installing the hose fittings. Apply a compatible pipe sealant to all connections. Keep the hose routing as straight as practical, and make all bends less than 45 degrees wherever possible. Use rubbercushioned Adel clamps every 18 inches to support the lines.
Run the discharge/fill hose from the pump to a place that will be a convenient location to position the waste/new oil containers. To prevent the remaining oil from dripping out of this hose after use, install a flare fitting and cap at the end.
Run a length of 14-gauge tinned copper wire from the pump to a 10A circuit breaker either on the ship’s main DC panel or on a conveniently located subpanel. Connect using solderless ring terminals that have been protected with shrink-tubing. For longer runs, you’ll need to consult the installation manual for wire size to maintain appropriate current.
Three Tips for Changing Oil
 Don’t Forget the Filter — Whenever you change the oil, be sure to change the filter. To avoid spilling waste oil, insert the filter into a Ziploc freezer bag. Use a filter strap wrench and unscrew. Keep in mind that the filter case will be hot, so wrap the filter/bag with a thick cloth to avoid burning your hands.
 Better Safe than Oily — It’s always a good idea to keep an oil pad under the engine oil pan and the waste reservoir in case some fluid leaks out. Put another in the bilge, under the filter, when you’re changing out the old one. It’s possible that you might drop it or that the plastic bag could spring a leak. Not fun.
 Make It Hot, Baby — Changing oil when it’s hot has two important advantages. First, warm oil flows easier through whatever pumping method you use. Second, warm oil will stir up the chemical and abrasive contaminants that have settled and would not otherwise be expunged.
There are alternative ways for changing oil. The simplest is a hand pump that draws hot oil through the dipstick into a waste container. More convenient is an integrated portable system that has its own reversible pump mounted to a collection container that holds the used oil. Jabsco makes one that allows the user to also refill the engine by filling the container with new oil.