To help Washington State Ferries investigate the use of a self-cleaning oil filtration system, researchers from Washington State University tested such a system on one ferry vessel, looking specifically at filtration effectiveness, environmental impacts, and costs. Results of filtration effectiveness showed little difference between the standard paper cartridge filtration system currently in wide use and the self-cleaning system. A life cycle environmental impact assessment revealed that although impacts from oil and filter use would be less, the additional diesel fuel consumed by that system would outweigh any benefits in many impact categories. Finally, a life cycle cost analysis suggested that the standard system would outperform the self-cleaning system in terms of whole life cost (unless the oil lifetime could be increased by more than three-fold), primarily because the self-cleaning system used additional fuel. The researchers’ overall assessment was that if expected costs and environmental impacts are major decision points, a suitable alternative system would need to consume less diesel fuel to be viable.