Fogging oil is a product usually composed of light oil with ashless corrosion inhibitors packaged in an aerosol can and applied as Blacksmith describes (or through the throttle plate for EFI engines) for long-term (i.e. winterizing) storage of engines, especially in severe (marine) environments.
FC-W spec engine oils already have robust corrosion protection built-in and may reduce the need for/benefit of 'fogging' in 4T engines using them.