I spotted this on the Windwing forum (www.windwing.com/forum):
"I thought I would add a tip†about lubrication!
There is a special product available from the yacht racing world called Mclube. It is designed for use on deck fittings like blocks and traveller cars. It is teflon based so it won't perish materials like sailcloth and synthetic ropes. I use it to lube my control bars - works really well."
I'm going to check West Marine for this, no doubt it will extend the life of your sheeting lines. Got to me some of that McLube! (For kiting)