The pump requires a small amount of power to operate. In fact, a [[Redstone Engine]] is sufficient to run it, though only very slowly. To operate at full speed, a [[Stirling Engine]] is required.
The pump does not distinguish between multiple kinds of fluid. In particular, when pumping [[Oil]] in the ocean, the pump will first attempt to suck up the entire surface of the ocean before proceeding deeper. To avoid this, you will need to manually isolate the area you'd like to pump from the surrounding area.
An easy way to do so is to place a [[Lily Pad]] on the surface of the water next to the oil patch, and then drop sand using the edge of the lily pad until it is above the surface of the water. If you do happen to suck up multiple fluids with a pump, you can use a [[Diamond Fluid Pipe]] in combination with an [[Void Fluid Pipe]] to dispose of the fluid you don't want.