A penetrating oil is a thin, oily liquid that is used to loosen rusted or frozen metal parts. It works by seeping into the tiny spaces between the metal surfaces and breaking down the rust or corrosion. A lubricant, on the other hand, is a thicker, oil-based liquid that is used to reduce friction between moving parts. It works by creating a barrier between the metal surfaces and preventing them from rubbing directly against each other.

You should use a penetrating oil when you need to loosen rusted or frozen metal parts. This could include bolts, nuts, screws, or other fasteners. Penetrating oil can also be used to free up stuck hinges, locks, or other mechanisms.

The best lubricant for your application will depend on the specific conditions and requirements. Some factors to consider include the type of metal, the amount of friction, the speed of movement, and the temperature. You should consult with a qualified technician to help you select the right lubricant for your needs.

The frequency with which you should lubricate your equipment will depend on the type of equipment and the operating conditions. You should consult with the manufacturer's recommendations for the specific equipment you are using.