A common method of preheating main turbine lube oil prior to rolling over the main unit would be to ________.

Correct Answer: Option C — operate the lube oil purifier on the main lube oil sump

Running the centrifugal lube oil purifier on the main sump recirculates and heats the oil. This effectively raises the oil temperature to operational levels throughout the entire system prior to pulling a vacuum or rolling the main turbine.