In this paper, the results of an experimental study on two phase (air and oil) flow through a crevice between two parallel plates are presented. These results are compared to the predictions of an approximate theoretical model. Four correlations are reported on the dependence of the friction factor on the Reynolds number based on the crevice hydraulic diameter and the crevice height. Each one of these correlations corresponds to a specific value of the oil to air volume ratio (μ) in the range 0≤μ≤0.3 The performance of the theoretical model was deemed acceptable for engineering estimates