Experimental fuels made up of cottonseed oil, transesterified cottonseed oil (methyl ester) and No. 2 diesel fuel have been compared to a baseline No. 2 diesel fuel in a turbo-charged, open chamber diesel engine. All fuel blends were analyzed and their properties compared to those of typical No. 2 diesel fuels. Test results include data on performance, gaseous emissions and limited (200-hour) cyclic durability. Crankcase oil samples were withdrawn at regular intervals during durability tests and analyzed for indications of fuel-lubricant compatibility. The paper presents the data obtained and discusses effects of fuel properties and engine operating conditions on the short and long-term response of existing diesels.