Abstract: An oil purifier for removing contaminants, particularly volatile contaminants. Oil enters an inlet, passes through a filter, a felt layer, a plurality of capillaries, and then spreads across an evaporation plate to an oil outlet. The oil is heated as it spreads across the evaporation plate, either by an external energy source or by hot engine oil, causing volatile contaminants to evaporate and be discharged out a second outlet. The gas pressure above the evaporation plate is kept substantially reduced below atmospheric pressure in order to minimize both the required evaporator plate size and the temperature of the oil spreading thereover and yet provide the desired evaporation rate of the volatile contaminants.