The generation of fine oil droplets by impinging an air jet on an engine oil surface represents a new mechanism of atomization. The process was studied using high-speed imaging and laser light scattering. The gas that penetrates the surface leads to the formation of liquid ligaments that enter the high-velocity region of the gas jet where they are atomized to produce droplets with diameters smaller than 5 mu m with a Sauter mean diameter of 1.21 mu m. The measured Sauter mean diameter was compared with a proposed semi-empirical analysis, and good agreement was found. The atomizer, based on this impinging air-jet mechanism, can be used to simulate the size distribution of oil droplets in engine crankcase ventilation and, therefore, is suitable for implementation in a laboratory test rig. (c) 2013 Elsevier Ltd. All rights reserved.