Oil immersed clutches are often treated without respect to the oil being present, i.e. the torque is assumed to be a pure dry friction torque, directly controlled by the actuating force. However, during the engagement this is sometimes not enough. The oil film acts in two ways: Firstly, the oil has to be squeezed out before dry friction can be developed. Secondly, before the friction surfaces have reached contact, the torque is viscous. This work proposes equations that take these phenomena into account. A simple model for the transition from viscous to dry friction is used. Compensation for grooves in the friction surface is made. Also the hydraulic actuating equipment (piston, return spring, orifice etc.) is modelled. Simulation results are verified by experiments.