"We work with corrosive materials, which start to break down parts over time. PEN® has been great in removing rust and keeping the machines well lubricated. It works better than any other penetrating oil I've used. Some of these machines are buried in mud. The parts become all rusted together. PEN® has the ability to penetrate all that build up and loosen the parts, so I can restore, repair, and re-assemble the tractors. It has definitely saved me time in disassembling pieces. It's a great product."