Varnish Mitigation: Relative Effectiveness of Non-Deposit-Forming Next Generation Lubricants vs. the Use of Varnish Removal Filters with their Conventional Counterparts
Matthew G. Hobbs, PhD, Peter T. Dufresne Jr.
Turbine lubricants employ a variety of base fluids. Mineral oil-derived base stocks remain the most prevalent, however, synthetics are becoming increasingly common. These fluids are exposed to severe oxidative stress during service, leading to breakdown and varnishing (the primary cause of downtime in gas turbine applications). Recently, PAGs have been positioned as varnish-free alternatives to more conventional mineral turbine oils. Our findings suggest that this claim is overstated. PAGs possess several advantages relative to conventional oils, however, well-formulated mineral oils proved almost as resistant to varnishing. Moreover, the risks associated with mineral oil varnishing can be effectively mitigated using established varnish-removal technologies.