07NAPLES-16 Effect of Lube Oil on the Physicochemical Characteristics of Particulate Matter Emitted from a Euro 4 Light Duty Diesel Vehicle Elias Vouitsis, Leonidas Ntziachristos, Zissis Samaras Lab of Applied Thermodynamics, Aristotle University Thessaloniki, GR 54124 Thessaloniki, Greece Loukia Chrysikou, Constantini Samara Environmental Pollution Control Lab, Aristotle University Thessaloniki, GR 54124 Thessaloniki, Greece George Miltsios Mechanical Engineering Dept., Technological Educational Institute of Serres, GR 62124 Serres, Greece Copyright © 2007 SAE International ABSTRACT This paper investigates the effect of lubrication oil on the physical and chemical characteristics of the particulate matter (PM) emitted from a Euro 4 diesel vehicle. Two different lubrication oils were examined. A fully synthetic ACEA grade B3 service–fill oil of low sulfur content (1760 ppm wt.) falling into the 0W-40 SAE viscosity grade and a mineral ACEA B2-98 motor oil of high sulfur (8890 ppm wt.), falling into the 15W-40 SAE viscosity grade. To exclude interferences from the fuel derived sulfur, a rather sulfur-free fuel (< 10 ppm wt.) was used in the experiments. The experiments included steady state tests, the certification cycle and real-world high- speed transient driving conditions. The properties measured included total particle mass collected on Teflon-coated filters, total particle number measured by a condensation particle counter, size distributions determined by a scanning mobility particle sizer. Chemical analysis was performed to investigate the metallic and the ionic character of the particulate matter for the different lubes. Results showed that the vehicle complies with the Euro 4 emission limits when tested over the type-approval NEDC regardless of the lubrication oil used. Both PM mass and number were drastically reduced with particle filter. INTRODUCTION Due to the substantial fuel economy benefit over its gasoline counterpart, diesel car is the key measure for reducing carbon dioxide and, thus, lowering the risk of dangerous climate changes. As a consequence, they are expected to overtake gasoline car sales in Europe and to form an emerging passenger car market in the US. However, diesel vehicles continue to be higher emitters of particulate matter (PM) and nitrogen oxides (NO x ) than gasoline ones fulfilling the equivalent emission standard. PM emissions have been significantly reduced over the last years and new vehicles complying with the Euro 4 standards emit below 25 mg/km, compared to ~100 mg/km 10 years ago. Future Euro 5 emission standards though (recently proposed at 3 mg/km) will be difficult to reach without the introduction of diesel particle filters (DPFs), which typically result to PM levels even below 1 mg/km [1]. In some instances DPFs have been seen to lead to the formation of a large number of volatile nanoparticles, especially at high loads [2-6]. The high nucleation rate has been attributed to the reduction in solid particle surface by the DPF, which enhances the homogeneous nucleation of sulfuric acid vapor [6]. Elimination of these particles will require strict control of the sulfur in both the fuel and the lube oil [7-9]. Fuel sulfur content in the near future is going to decrease into very low levels (as low as 1 ppm). When using very low sulfur fuels, the effect of the sulfur in lubricating oil may become dominating. Several studies have shown that lubricating oil contributes significantly to the engine-out PM yield accounting for 25% of the total PM mass emission in heavy – duty applications and somewhat lower in light – duty applications [10-11]. In this framework, the present work investigates the effect of two lubricating oils of different origin (synthetic vs. mineral oil base) and sulfur content on NO x and PM emissions from a current technology (Euro 4) diesel passenger car. The study includes measurements of gaseous pollutants, the NO 2 /NO x split, particle size and number concentration and particle chemistry. To minimize any fuel effect we used an ultra-low sulfur fuel. The same vehicle is then retrofitted with a catalyzed DPF (CDPF) to examine the effect of this technology to all emission parameters studied. It is expected that the results of this study will provide useful experimental support to all discussions related to future emission standard formulation.