Abstract: Disclosed is a pressurized internal oil management system, comprising an oil dam, at least one oil separator, at least one oil collection manifold, at least one oil pump, and one or more paths for returning the separated oil; said system integrated within the casing of a fluid displacement device to supply adequate lubrication regardless of orientations under zero to full gravity, and methods and applications related thereto. Fluid displacement devices useful herein include oil lubricated rotary or reciprocating machinery, such as compressors, expanders, pumps and engines, in the casing of which exists one or more drive mechanisms that can be utilized to operate the oil management system, in most cases without even increasing the size of the casing.