Check out "Pro Towels". They're impregnated with an oily "Citrus-Solve" type fluid. Just run the chain through a folded towel or 2 until it starts coming clean. They come in a big tub for home & individually packaged towels for use on the road. At home I make extensive use of compressed air to get the crud out of tight spots. A few times while out on the road, I've run across auto & bike shops that have let me use their compressed air hose for that purpose.