A 1000-hour test was conducted to determine the durability effects of 2-ethylhexyl nitrate (2-EHN) cetane improver on heavy duty diesel engines. Two identical 1993 DDC Series 60 engines were run side-by-side on a severe duty cycle. Both were fueled with a commercial low sulfur fuel. The fuel in one engine was treated with 7500 ppm of 2-EHN cetane improver. At the end of the test, engine wear and deposit comparisons were made to determine the effect of high cetane improver treat rates on engine durability.After 1000 hours of operation, the engine running on fuel treated with 2-EHN cetane improver exhibited lower engine wear and deposits than the engine run without cetane improver. Analysis of oil samples drawn every 100 hours indicated no difference in wear metals or other physical properties when cetane improver was used. Fuel analyses demonstrated that 2-EHN did not degrade under the high operating temperatures of this modern heavy-duty diesel engine.