It sounds like a good, thick, durable lubricant is necessary for your application. You might want to try Phil Wood's Tenacious Oil. It's probably one of the thicker, stickiest oils for bikes, see http://www.philwood.com/Price%20List/P17.pdf It may be available at LBSs in your area.

Although it is a great lubricant, it will attract dirt and goo. However, if a lubricated and protected chain is your priority, this is probably the ticket.