A standardized test to evaluate engine performance, durability and oil life was conducted on a 10.3 liter 3176B Caterpillar diesel pilot ignition natural gas “dual fuel” engine. The testing was performed at the Caterpillar Technical Center in Mossville, Illinois. The engine durability evaluation included engine disassembly with both dimensional and visual inspection of key components. Engine performance was monitored throughout the test and oil analysis was performed at regular intervals. The technical results support the conclusion that engine life and oil life of a dual fuel (natural gas) engine will meet or exceed typical diesel values and that engine performance will remain within factory specified limits for the life of the engine.