A developmental aero gas turbine engine, embedded with rotating components needs to be supported with a well-designed lubrication system to address its friction, heating and cleansing requirements. To ensure and sustain the intended lube systems performance, apt and timely maintenance by continual monitoring of its performance parameters are desirable. Instrumenting the lube system and developing models to predict the feasible performance parameters are the approaches which go hand-in-hand to handle the transition from lavish ground trial instrumentation to the scanty flight trial instrumentation. This paper depicts a data prediction model which has been developed, validated and deployed for the temperature measurement in the lubrication system using the cooler temperature of an aero gas turbine engine under development. The data thus predicted as a virtual sensor, not only supplements the thermo-couple measurement during the ground trials, but also ensures its confident usage in the absence of thermocouple measurements during flight trials.