Airborne and Structure-borne ultrasound has evolved into a technology that many would consider to be the cornerstone of an effective condition based maintenance program. From leak detection, electrical inspection, and various mechanical inspections, ultrasound is truly a versatile tool for anyone's PdM "toolbox." One application in particular is to utilize the technology for condition based lubrication and to prevent over lubrication in rotating equipment. This presentation will show how using structure-borne ultrasound, one can detect mechanical faults in rotating equipment and prevent failures due to over lubrication.