I use silicone spray on my rudder cables and pivots. -- no grease, no undesirable residue, no gumming up. The carrier evaporates, leaving nothing but friction-reducing silicone.
Interesting comments about the rudder. I relied on the tensioning knob to adjust rudder slack -- had no problems setting any tension wanted once on the water. I found that any slack in the line tended to exacerbate the boat's tendency to wander, so I preferred a taut line to minimize helm correction (not so tight as to jamb the control).
Equalizing the rudder deflection is also an easy adjustment. For that, you need the rudder up (which also centers it). You also need line slack. This can be accomplished by loosening the tensioning knob until the rudder control slides freely. It is then positioned in the center of its throw (depending on which side of the seat the control is mounted on, about 45 degrees outboard). Finally the tensioning knob is tensioned at least a turn to lock the rudder cable in its new position, and further tensioned to take up any slack in the system. Recheck and adjust as necessary.