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B͒ Based on the experiment, an oil’s propensity to produce insolubles does not appear to be related to its oxidative stability. ͑c͒ When selecting turbine oil, one should consider the fluid’s resistance to form sludge and varnish as an important criteria. ͑d͒ There is a need for a new industry test standard to measure turbine oil’s oxidative characteristics and varnish/sludging tendencies. 3. Turbine Oil Condition Monitoring ͑a͒ RPVOT may have limited value in a condition monitoring program due to the lack of correlation to turbine oil varnishing performance.

Although this has a slightly lower initial RPVOT value than oil D it performs better in the FTM laboratory evaluation test, with minimal thickening, acidity increase, and lower sludge formation indicating even greater oxidative stability and deposit control under the severest gas turbine conditions. As discussed later, it is typically the rate of decline of RPVOT when the oil is in service, rather than the magnitude of the starting value that is of key importance in determining the oils performance.

Also, many power stations are operated in a peaking or cycling fashion, which places further thermal stress on the lubricant. Turbine oil formulations have kept pace with these changing operating environments. S market utilize API Group II ͑hydrocracked͒ or higher basestocks. These products contain significantly fewer impurities than solvent refined API Group I products. Furthermore, these lubricants employ more sophisticated and robust additive systems to improve oxidative stability and a host of other performance factors, making the formulations more suitable for today’s demanding environment.