Quantifying the contribution of lubrication oil carbon to particulate emissions from a diesel engine

The contribution of lubrication oil to particulate matter (PM) emissions from a Cummins B5.9 Diesel engine was measured using accelerator mass spectrometry to trace carbon isotope concentrations. The engine operated at fixed medium load (285 N-m (210 ft.lbs.) at 1600 rpm) used 100% biodiesel fuel (B100) with a contemporary carbon-14 (¹⁴C) concentration of 103 amol ¹⁴C/mg C. The ¹⁴C concentration of the exhaust CO₂ and PM were 102 and 99 amol ¹⁴C/mg C, respectively. The decrease in ¹⁴C content in the CO₂ and PM are due to the consumption of lubrication oil which is ¹⁴C-free. Approximately 4% of the carbon in PM came from lubrication oil under these operating conditions.