I use WD-40 as a cleaner. Tools, hinges, whatever I want to clean some mild grime off whilst leaving a light protective coating on. I concur with almost everyone in this thread...as a penetrant, WD40 is next to worthless. But I find penetrating oils like PB-blaster are too smelly and grimy to use for anything other then loosening fasteners...so for everything else, there is WD-40. Doesn't overly smell, its clear, and leaves a nice shine that isn't sticky or greasy looking. Makes for a good engine detailer too, though it can attract dust. As a rust protector, its very good.