Recent developments in engine production focus on downsizing strategies in order to meet ecological restrictions while improving efficiency. However, abnormal combustion phenomena limit further improvements since premature ignitions, which occur at higher engine torque and lower engine speed, initiate severe knock in the subsequent combustion. In order to get to the root of the problem, investigations on this topic revealed that lubrication oil mixed with fuel increases auto-ignition of the mixture and hence causes pre-ignitions, if oil-fuel mixture droplets enter the combustion chamber and heat up. Therefore, the main problem is that mixing of lubrication oil and fuel can take place in liquid film accumulations. Within this thesis, the pre-ignition tendency of a direct injection gasoline engine is explored and investigated in detail conducting numerical simulations. Since the injection process has proven to have a huge impact on mixture preparation, droplet disintegration models for primary and secondary break-up are investigated with special attention for the validation of the numerical injection set-up against measurement data. A multicomponent fuel model is applied in order to represent the boiling behaviour of real gasoline as realistic as possible. By comparing two different injector types, the injection process and wall-film formations are investigated with regard to possible mixing of fuel and oil. Liquid film accumulations at the cylinder walls and in the piston crevice are identified and investigated for each injector type. Detailed investigations on mixture preparation and charge motion revealed that steep into the cylinder orientated injector axes are advantageous. Improvements in mixture preparation and a minimised mixing with oil is observed. Results show that the numerical prediction of wall-film structure can be correlated to test-bench observations. Therefore, the gained factors contribute to a better understanding and hence to avoid pre-ignitions.