A heavy-duty pickup truck with a 5.9-L diesel engine was targeted to operated on a blend of 20% methyl esterof rapeseed oil (RME) and 80% 2-D diesel (2-D) for 161 000 km (100,000 miles). The actual blend used was 27.9% RME.The engine was unmodified, but modifications were made to the vehicles for the convenience of the test. Fuel mixing wasdone on-board to extend the driving range to over 5000 km (3,100 miles) between biodiesel fill ups. Rusting of the mildsteel fuel tanks contributed to fuel filter plugging which was eventually solved by changing to stainless steel tanks andswitching to a different fuel supplier. Chassis dynamometer testing, injector coking, engine compression, injector valveopening pressures, and engine oil analyses were completed at regularly scheduled intervals to monitor the engineperformance parameters. RME produced 5% less power than 2-D, while 20RME produced 1.5% less power than 2-D.Smoke density was reduced 32% with RME, while 20RME increased smoke density 6.6% higher than that of 2-D. Theresults of the oil analysis showed that there was no unusual deterioration of the engine, or any unusual change in oilcomposition from using the biodiesel fuel. Using aluminum and iron as comparison analysis, the test vehicle averaged2.2 ppm for aluminum and 8.0 ppm for iron, the first check vehicle averaged 2.4 ppm for aluminum and 8.5 ppm for iron,the second check vehicle averaged 5.4 ppm for aluminum and 20.0 ppm for iron, and a third check vehicle averaged 5.7ppm for aluminum and 64 ppm for iron (the third of four samples showed iron at 183 ppm with the others at 20-28 ppm.)Engine compression and injector valve opening pressure remained constant throughout the test. Emissions tests with achassis transient dynamometer at the Los Angeles Metropolitan Authority Emissions Test Facility resulted in a decrease inHC (20%), CO (25%), NOx (2.6%), PM (10.9%), and there was no difference in CO 2 with 20RME compared to 2-D.When the vehicle reached 163 800 km (101,785 miles) the diesel engine was removed from the truck and shipped toCummins Engine Company in Columbus, Indiana, for analysis. The condition of the engine obviously reflected the lightload condition used in the pickup. However, it was generally considered to be in a condition which could be characterizedas good or better than that which would have been expected with diesel fuel. Engine parts were clean and showed littlewear. Adverse effects were hardening of the crankshaft seals which made a slight depression where they made contact withthe shaft; and rusting of the fuel filter attachment stud. The fuel pump, although showing varnish, was found to be in goodcondition in the bench test.