Impacts of Biodiesel Fuel Blends Oil Dilution on Light-Duty Diesel Engine Operation 2009-01-1790

Increasing interest in biofuels—specifically, biodiesel as a pathway to energy diversity and security—have necessitated the need for research on the performance and utilization of these fuels and fuel blends in current and future vehicle fleets. One critical research area is related to achieving a full understanding of the impact of biodiesel fuel blends on advanced emission control systems. In addition, the use of biodiesel fuel blends can degrade diesel engine oil performance and impact the oil drain interval requirements.

There is limited information related to the impact of biodiesel fuel blends on oil dilution. This paper assesses the oil dilution impacts on an engine operating in conjunction with a diesel particle filter (DPF), oxides of nitrogen (NO_x) storage, a selective catalytic reduction (SCR) emission control system, and a 20% biodiesel (soy-derived) fuel blend. The main focus was on the biodiesel oil dilution levels observed during an accelerated aging protocol and an assessment of the potential impacts on the engine and emissions control systems. For the NO_x storage system (which requires a late in-cylinder fuel injection for regeneration), biodiesel oil dilution levels ranged from 5%–10%. For the SCR system (which used a urea solution as a reductant and late in-cylinder fuel injection for diesel particle filter regeneration), biodiesel oil dilution ranged from <4%–8%. These observations were made over typical oil drain intervals. Despite these observed biodiesel oil dilution levels, there were no observed impacts on performance of the engine or the emission control systems.