Abstract:The oil pump is one of the most important parts for the engine. Its function is to provide oil for engine lubrication system and supply hydraulic pressure for some parts. So the efficiency of oil pump is very important. At present, there are mainly two kinds of medium detection performance of oil pump, i.e., gas and oil. The gas has many benefits, which are different with the use of the environment medium. By using the experimental data provided by DPCA, the correlations between gas and oil are discussed in this paper.