I'm also a firm believer in the silicon sprays. You can use anything, including the generic food safe silicon spray cans, but I use MooSlick from CowRC. I find with it I only have to shoot something once when it is clean to get good lubrication once it dries, rather than several times like with the others.

Note: Silicon spray is not meant to clean, nor is it meant to prevent dust. It will, however, keep things moving, and make it easier to clean the dirt off later.