Simple Green comes in two formulations - the green all-purpose cleaner and the purple heavy-duty cleaner.
I use the purple heavy duty full strength in my parts washer. It removes dirt and grease buildup simple and easy. I keep a spray bottle handy for cleaning around nuts and bolts prior to trying to loosen them and cleaning the hard to reach corners.
I find Simple Green does better as a powder and copper solvent for cleaning guns than the old standby Hoppes #9.
Non-toxic, bio-degradable, and multi-purpose. A great economical cleaning agent to have around the shop...