This Biodiesel Research portion of the DOT Alternative Fuels Study covers three research areas: an Rochester Institute of Technology (RIT) Vehicle Fleet Study; Component Wear Studies; and an Engine Durability Dynamometer Study. All three areas are complementary, and the results of the cumulative study should add to the current understanding of the effects of biodiesel in modern engines used in the transportation industry. The RIT Fleet Study included the use of two medium-duty diesel vehicles used exclusively on the RIT campus. The two vehicles were used for different purposes, and the operating profiles were significantly different. Fuel economy, emissions and maintenance histories were compared with the engines operating on a range of fuel blends from Ultra Low Sulfur Diesel (ULSD) to B90 over a four-year period (2007- 2010). Fuel economy was monitored over the duration of the study and comparisons were made as to the efficiency of ULSD, B20, B20 with 30% kerosene and B90. Since B90 was only used in the warm summer months, the seasonal variation in fuel use overshadowed changes in fuel efficiency caused by the fuel blend. Since the impact of biodiesel use on CO emissions is well documented, more emphasis was placed on nitrogen emissions, specifically the combined NO and NO₂ species known as NOx. In the idle test, one vehicle showed increased NOx and the other showed reduced NOx. The general tendency with both vehicles during the driving test was that increased biodiesel fraction caused increased NOx. However, vehicle condition and type of use appear to impact NOx emissions more than fuel blend. Finally, there were no cold fuel problems when using B20 with kerosene (20% biodiesel, 50% ULSD and 30% kerosene) during the winter months in Western New York. Neither the vehicles nor the fueling station had any fuel-related problems over the study period. Two component studies were performed. One investigated the lubricating properties and oxidation propensity of engine lubricating oil when diluted with biodiesel fuel. The other investigated the changes in lubricating properties of ULSD when mixed with biodiesel. Using a reciprocating wear tester, the first study found that a small amount of biodiesel (2%) in lubricating oil improved the lubricity of the oil. Up to 10% biodiesel dilution continued to improve lubricity. When heated to 300°F during testing, no oxidation was detectable. The second study used a standardized high speed wear tester to compare wear characteristics of parts lubricated in ULSD with various quantities of biodiesel added. In all cases, increased biodiesel quantity reduced wear on the test specimens. The Engine Dynamometer Testing was run in three parts: a Gage R&R Study, a Fuel Screening Study, and a Durability Study. The Gage R&R Study was performed to document variation in RIT’s new engine dynamometer lab and the test engines. Results from that study are summarized in this report. The Fuel Screening Study looked initially at the effect of five fuel blends on exhaust emissions, performance and efficiency. As the biodiesel ratio increased, NO by increased (+4.5%), but the smaller quantity and highly toxic NO₂ decreased (-6%). So too, CO (-17%) and Soot (-81%) decreased with increased biodiesel blends. Fuel torque and fuel speed interactions were found significant to CO production as well. With the exception of soot, operating conditions affected the emissions more than the fuel blend. On the dynamometer, for a particular operating condition, efficiency decreased by approximately 6% as the blend increased to B90. Maximum available torque decreased by 8.5% and peak engine power by 17%. The Durability Study focused primarily on wear and maintenance items but looked at emissions, performance and efficiency with greater resolution. Two identical 6.5L Cummins ISC engines were run on different fuels for 1500 hours each. ULSD and B100 were used as the test fuels. Periodic tear-downs allowed inspection of all typical wear parts to document the aging process. Statistically, no fuel effects on wear items (differences between engines) could be confirmed. Fuel filter problems were persistent throughout all of the B100 operation and completely absent during ULSD testing. Similar results were seen for performance, efficiency and exhaust products as found in the Fuel Screening Study.