Parts Washer cleaner

Good 'ole Stoddard solvent is what I've been using. It's pretty close to being mineral spirits, and usually what's on the drum the guy pumps it out of for me. High flash point, fairly high vapor point so it doesn't evaporate very much. If you can rig up a filter to go with the pump, your "charge" of solvent can last a long time and with the hose or wand you'll clean the parts with clean solvent instead of recirculated dirty solvent.