When metalworking fluid suppliers discuss “EP metalworking systems”, or extreme pressure additive containing systems, the type and formulation basis for these systems can be as wide and varied as the applications that they are found in. The term “extreme pressue” classically refers to the property of lubricants which impart to rubbing surfaces the ability of carrying appreciably greater loads than would be possible with ordinary lubricants without excessive wear or damage. How a formulator is able to produce such system properties is entirely dependent on the type and combination of EP additives selected for the system.