What metals ? cast iron ? aluminum ?
old school parts washers used a solution of sodium hydroxide (lye) but you wouldn’t put aluminum through them
Some part stores still sell small buckets of carb dip with a strainer and or you use to be able to pick up aerosol cans of carb cleaner at the .99 cent store
Tide detergent and hot water or any degreaser but stuff like Simple green does a number on some plastics
transmission oil or deep creep foaming cleaner , goop-off but again not plastics friendly
Brake cleaner a portable steam cleaner , baking soda and vinegar , soaking for a few hours, “solvent alcohol” wipe down, agitators or vibrating abrasives containers like rock hounds or jewelers use for small pieces, nuts , bolts .
Or if money’s no object a Dry ice blaster.