Grease is always good for surfaces that have relative motion between them. For the flap tube and rudder pedal bushings I used a standard automotive white grease. For metal to metal stuff (like the gear legs into the gear leg weldment) I use the AeroShell grease in the hangar - but any will do. Same for the nose gear hinge bushings.
Greasing the gear legs before mounting prevents the two steel parts from corroding and becoming one. At some point you might need to take one or both out.
Carl