Jobst Brandt used to say that clean water was a perfectly good lubricant for a bicycle chain. Of course, even Jobst couldn't stop the rain— er— stopping. Then the chain would squeak mightily.
Jobst would also stop at a service station and beg a little of the oil drained at an oil change on a car. Or just pick up the "empty" can and dribble a few remaining drops onto his bike's chain. It doesn't take much.
These stories always made me wonder whether the people giving the lanky, taciturn cyclist a thimbleful of oil for his chain knew they we're touching the hand of a demigod among engineers...
Andre Jute
Coming up for 1000km on the factory lube, no extra oil