Due to the demand for higher efficiency, gas engine designs are changing in that gas engine oils are exposed to higher thermal stress and face challenges regarding the prevention of deposits. In this work, the “oil chute” laboratory test was used to study the high-temperature deposit-formation tendency of various paraffinic and naphthenic base oil blends. The oil chute is a setup that circulates oil through two different temperature zones, the hot zone being a heated metal chute that triggers deposit formation. In addition, the thermo-oxidative stability of the oil blends was investigated using an artificial alteration method. The results showed that naphthenic base oils have the capability of substantially reducing high-temperature deposit formation. However, they tend to degrade faster under thermo-oxidative stress. Therefore, finding the right balance between paraffinic and naphthenic base oil components will allow the formulation of gas engine oils that provide the right properties to cope with the higher stress levels they are subjected to in modern gas engines.

Dissolved gas analysis (DGA) is the most widely used technique for monitoring transformer condition and detecting faults at an early stage. The quantity and type of gases that are produced by transformer faults and dissolved in the insulating liquid can reveal a lot about the nature and severity of the fault. To explore the variations in the dissolved gases based on the severity of the fault and the type of insulating liquid, we employed the Tube Heating Technique to simulate thermal faults at regulated temperatures up to 800 °C. To illustrate these differences, DGA data from commercially used insulating fluids such as inhibited and uninhibited mineral oils and a natural ester, will be presented.