A lubrication system for a heavy duty gas turbine includes a bearing lubrication assembly coupled to the bearing and an oil and vapor extraction assembly disposed in a cavity defined by a bell mouth hood in an air inlet duct. A high volume vacuum blower is coupled to the oil and vapor extraction assembly to provide a relative negative pressure. An oil and vapor separator is disposed downstream from the high volume vacuum blower. The lubrication system also includes a control subsystem that maintains a cavity pressure lower than an air inlet pressure.