I have used liquid dish washing detergent in warm (as warm as you can stand to put your hands in it ) water...
An old margarine tub, or mixing bowl with a snap on lid...let the part soak for a few minutes, jiggle/shake the bowl occasionally, then scrub w/ tooth brush. Rinse w/ warm water...then oil w/ TAL-5 or similar spray lube.

I've only used this method with non ferrous metal parts...with Steel I use carb cleaner, or acetone, or lacquer thinner and lots of q-tips...then light oil for protection asap.