A system determines which propulsion-generating vehicle or vehicles in a group of propulsion-generating vehicles have an increased risk for oil carryover during operation at an idle setting for at least a designated oil carryover commencement time period. The system also determines a power requirement for the group of propulsion-generating vehicles in the vehicle system. The system determines power outputs for the propulsion-generating vehicles in the group such that the propulsion-generating vehicle or vehicles having the increased risk for oil carryover do not operate at an idle setting for longer than the designated oil carryover commencement period, and that the power generated by the group of propulsion-generating vehicles meets the power requirement that is determined.