The piston ring pack is important for the sealing of the combustion chamber of an internal combustion engine. It plays a major role in friction, wear and oil consumption considerations. Both experimental and theoretical studies in this area are difficult due to the complexity of this highly dynamic system. The paper deals with the numerical investigation by means of computational fluid dynamics of the gas and oil flow in the piston ring pack. Having been validated with experimental data, the simulation results show gas and oil transport mechanisms, which can be used to improve existing models of 0D/1D-simulations. This leads to a better understanding of the processes in the piston ring pack and helps to further optimize the tribological system. (C) 2016 Elsevier Ltd. All rights reserved.