One question that you will often hear with regard to commercial compressors is how much oil pressure they need to operate. The oil pressure required will depend on the size, type and intended use of the system. The age of your compressor may also affect oil pressure, because older compressors have more worn parts, which creates gaps that allow for extra oil to flow, thereby reducing pressure in the system. As you compare different compressor types and oil pressure requirements, it is important to understand the difference between useful or net oil pressure and discharge oil pressure. These two measurements apply to different parts of your system, and you must understand which is which to ensure that your compressor is properly lubricated and operating normally.