This document provides guidance and requirements for the maintenance in service of mineral oils used as lubricating oils and control fluids used to lubricate steam, gas and combined cycle turbines in service.

This document is applicable to lubricants classified in ISO 6743-5 and specified in ISO 8068, except the grades TSD, TGD and TCD (phosphate esters) for which ISO 11365 is more relevant, and the grades TGCE, THA, THCH, THCE and THE.

This document also gives guidance and requirements with respect to the corrective actions that are taken to maximize service life.