The bearings or bushes on these things are made from a porous bronze called 'Oilite' and they are lubricant impregnated from manufacture. However they do dry out (hence the squeak) but you can re-oil them if they are accessible. You could also use WD40 for a similar short lasting effect, but try to aim the lube into the bush itself, rather than just applying indiscriminately.
John, July 2008
