I recall one "OLD" biker back in the day advising me to use a lot of VARSOL on my chain to clean it, then apply lube. Others used to remove the chain, clean it then soak it in a bath of Lube. Newer "O" ring chains a LOT easier to maintain.
I've used kerosene to attempt a rejuvination of a chain on several project bikes, soak it in a pan for a couple of days, attack with a bristle brush, wipe it dry, then hang it and apply oil of choice. All non-o-ring chains, of course. Worked OK. Scott oiler on my daily bike.