Penetrating oil is used to lubricate and remove rusty bolts and nuts without breaking them. After spraying the corroded part, the oil seeps into the small areas of the stuck part. Once the bolt or nut is lubricated, it may be able to be removed without damage. Penetrating oil displaces rust-causing moisture with an oil coating, and fogging oil works in much the same way. It is used to prevent corrosion in a stored engine. A thin film of oil is left on the cylinder walls where engine oil has run off to keep the cylinders from rusting while the engine sits. Check out O'Reilly Auto Parts' selection of fogging and penetrating oil for a product that fits your needs.