A computer model was developed to allow for parametric studies of engine lubrication systems. A case study of a four-cylinder gasoline engine is presented in this paper. Mathematical models describing the oil flow through the hydraulic tappet, oil jet, and plain journal bearings are also presented. The flow from an oil pump and the flow resistance through an oil filter are considered at various temperatures. Various design guidelines are applied in the analysis. The effect of oil aeration on the engine lubrication system is examined. The flow and pressure distributions are calculated and the pressure data is compared with experimental data at various locations within the engine lubrication system. This new computer model can be used to facilitate the engine lubrication system design process.