Alloy seat post sticking

[Garry Booth]

The (very long) seat post of my Dahon folder is increasingly difficult to move up and down. Since you have to move it up and down when folding, that is quite a pain.
It is well scarred and clearly oxidising. How can I keep it moving freely and not jamming completely? Should I rub it down with emery paper or something?

[thirdcrank]

As it sounds as though you can still get it out, I'd use some light grease to lubricate it before you find it's truly stuck. Not ideal, of course, but much better than the alternative. I suspect that rubbing it down would just remove any vestiges of remaining surface protection and the corrosian would just get worse.

[hubgearfreak]

rubbing it down would take off the existing corrosion, but i'd be wary of emery cloth.

use metal polish to clean it up, and like TC says, grease