Well, that page sells grease and grease nipples for the system
Bavaria didn't fit the grease nipples on ours, so I used silicone oil (safe around plastics) where the vertical wires come down from the steering pedestal. It nicely ran down the wire into the conduit and the steering became very smooth and together with an overhaul of the rudder bearings you could move the wheel with a pinky finger. It lasted a very long time, perhaps because the wires go up on both ends, so the oil mostly stays in.
Ours didn't have any signs of corrosion, but it also is in a very dry, well heated part of the boat (engine compartment) on the 40 Ocean.