The dependence of the differential pressure drop Delta p and the level of internal oil saturation S on the flow velocity of the air were investigated experimentally for a typical oil mist filter composed of oleophilic glass microfiber layers. Over a wide range of filter face velocities (nu = 5-70 cm/s) and liquid loading rates (R = 15-125 mg/(m(2) s)), and within the accuracy of the measurements, the "wet" pressure drop of the filter Delta p-Delta p(0) (i.e. the increase in Delta p over the "dry" pressure drop Delta p(0)) was constant and did not show a systematic dependence on nu. When decomposing the wet pressure drop into its components Delta p-jump and channel-Delta p, the Delta p-jump was also independent of the oil loading rate. The level of internal liquid saturation S was inversely proportional to nu, with an empirical fit function S = 1/(1 + nu/nu*). The characteristic velocity nu* was found to depend on the oil loading rate, and presumably also depends on the media structure which was not varied here. This filter behavior is consistent with the "jump-and-channel" model proposed recently by Kampa et al. (2014). The experiments further showed that the "steady-state" pressure drop under constant filter operating conditions underwent a gradual increase with time (termed "Delta p-creep") that depends on operating conditions. This Delta p-creep diminishes gradually and was found to become stronger with increasing loading rate and filter face velocity. At the highest rate of increase (i.e. nu = 70 cm/s, R = 125 mg/(m(2) s)), an experiment lasting for 1100 h did not suffice to attain an asymptotic level for Delta p. Creep was found to be associated with a gradual increase in saturation and must therefore be classified as an(other) instability phenomenon in oil mist filters. (C) 2017 Elsevier Ltd. All rights reserved.