I don't buy the metal in old engine oil theory, if, as its suggested, the oil is full of metal particles it would destroy your engine in seconds, sure its thiner but still far better at lubrication than most chain lubes.
I've also used a rag soaked in oil in the past, wrapped the rag around the chain and slowly rotated the wheel, I found that not only covered the chain in oil but also wiped off any dirt and dust that had built up on the links. Bloody messy though lol