I use Remington gun oil, a well stocked cleaning kit, Ivory soap chips, and "everclear". Generally, I drop the "dirty" cylinder(s) into a pan of near-boiling soapy water and cook it in there for about 10 minutes, allowing stuck nipples to loosen a bit. Then I remove the stubborn nipples with a NEW nipple wrench... very carefully.. Clean the cylinder and nipples.. dry off. and wipe & swab in everclear to get rid of moisture. Oil all parts lightly and reassemble. That's how they did it and that's the way I do it to this day.
Thanks for reading,
Cliff