Abstract: Apparatus and methods for improved in-line contaminant removal from engine lubricating oil are provided which employ gravity to achieve a desired flow rate of oil. The invention is adapted for use with an existing engine oil lubrication system and continuously processes a side stream that after processing, is returned to the engine oil. During processing, the oil is first filtered and then drained and deposited upon the upper central surface portions of a heated dome whereon the oil forms a thin film from which relatively low boiling volatile impurities (especially water) are rapidly separated in a gaseous state. The gas is vented through a pressure relief valve to the manifold while the recovered reconditioned oil is collected and recycled.