8 Ounce Case Of 12-Mousemilk (Blue) Penetrating Oil. This is a replacement for the original design fr use in areas were VOC's are a consern. Mousemilk Blue is vegetable oil based. It can be used anywhere Mousemilk Green is used during disassembly. The light oil penetrates deeply into the threads of frozen and rusted fasteners. Not recommended for long term lubrication.