This SAE Aerospace Information Report (AIR) provides information and guidance for the selection and use of technologies and methods for lubrication system monitoring of gas turbine aircraft engines. This AIR describes technologies and methods covering oil system performance monitoring, oil debris monitoring, and oil condition monitoring. Both on-aircraft and off-aircraft applications are presented. A higher-level view of lubrication system monitoring as part of an overall engine monitoring system (EMS), is discussed in ARP1587. The scope of this document is limited to those lubrication system monitoring, inspection and analysis methods and devices that can be considered appropriate for health monitoring and routine maintenance. This AIR is intended to be used as a technical guide. It is not intended to be used as a legal document or standard. This SAE Aerospace Information Report (AIR) was developed to provide information and guidance for the selection and use of technologies and methods for lubrication system monitoring of gas turbine aircraft engines. Benefits of effective engine lubrication system monitoring include increased reliability, reduced cost of ownership, improved product assurance, and enhanced safety of the equipment. The guidance within this report will support developers, operators, and maintainers to improve the effectiveness of lubrication system monitoring in existing and future applications. This edition updates content, formatting, and incorporates new content on oil quality monitoring and off-aircraft oil debris monitoring.