David, potentially dodgy stuff Silicon spray and WD40 if not very careful, especially if accidentally breathed in.

 I would recommend a cream/paste/oil/track lub'   Scotty

Two to one tackle on the genoa sheet works beautifully but one word of caution. The weight of the block on the clew of the sail makes a lethal weapon for any one on the foredeck during a tack of while hoisting or lowering the sail!

Keep well clear and warn any new to your boat to do the same.