For small items, I use a large capacity vibratory cartridge case cleaner with sand. This works great on items ranging from bolts to thermostat housings. Yeah, the sand and car parts may be beyond what the cleaner was designed for, but it's still working. One of my vehicles had special factory bolts marked CDPD (Chrysler, Dodge, Plymouth, DeSoto). Those are tough to find, so I needed to salvage as many as possible. They cleaned up real well in the vibratory cleaner.