Lubricating mast track
Graphite-based grease (e.g. the kind you can buy at the auto parts store to lube a speedometer cable) will be a terrible choice, IMO. It''ll end up on your sails and will collect dust/dirt/salt. It''s truly amazing how much dirt accummulates on a boat anywhere near land.
Practical Sailor has done this topic several times, and they have opinions about what non-accumulating lube works best. But I''m so pleased with MacLube, I''m sticking (no pun...) with what works well for us.