A pin assembly for insertion into a pin joint of an aircraft landing gear is disclosed. The pin assembly includes a reservoir for storing a lubricating agent and a piston mounted for reciprocal movement within the reservoir, the piston dividing the reservoir into a first chamber and a second chamber. A bi-directional flow path between the first and second chambers via the surface to be lubricated is provided by means of a first bi-directional flow path between the first chamber and the exterior of the pin assembly and a second bi-directional flow path between the second chamber and the exterior of the pin assembly. A pin assembly including an indicator system, and a pin insert in the form of a replaceable cartridge is also disclosed along with associated methods.