This product is somewhat more pricey than your typical can of WD40, but it's the sustainable and greener alternative.

There are lots of spray lubricants that penetrate and loosen stuck and rusted metal parts, lubricate tools and hardware, and inhibit corrosion. Bio-Greaser does the trick without the petroleum oils, hazardous solvents, synthetic propellants and other chemicals conventional products contain. New technology converts renewable soybean oil into a stable, highviscosity, industrial-grade lubricant you can use safely indoors and out to penetrate and protect metals and plastics. Fully biodegradable. 14 oz. CO2-powered spray can. (via gaiam.com)