When I have drained the oil tank I have not put that much effort in it.
1) run a 5/8" line up through the right drain hole in the back,
2) feed it under the intake, up to near the tank,
3) pinch off the supply line to the oil filter,
4) disconnect the oil filter at the inlet side,
5) plug the 5/8 tubing on the end of the tubing coming out of the tank
6) put a nice clean jug under tubing left hanging out of the drain hole,
7) take off the clamp on the line to the tank,
8) let gravity work the magic,
9) go have a beer, or two (or your favorite cool beverage),
10) tilt up the craft or tank to get out the residual,
11) once the tank is empty, disconnect the 5/8 line, and hold it up high enough til all the oil is drained,
12) pull line from the hull,
13) change the oil filter while you have the chance,
Very little oil left in the hull, especially if you raise up the oil filter higher than the pump when you disconnect it.
