This Technical Specification applies to mineral oils used as lubricating oils and to control fluids used to lubricate steam, gas and combined cycle turbines in service. The lubricants considered in this Technical Specification are those classified in ISO 6743-5 and specified in ISO 8068. This Technical Specification is intended to ⎯ help power equipment operators evaluate the conditions of the oil in their equipment and maintain the oils in serviceable conditions; ⎯ help users understand how the oils deteriorate and carry out a meaningful programme of sampling and testing of oils in use. This Technical Specification also gives instructions with respect to the corrective actions that are taken to maximize service life.