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New environmental regulations and stringent emissions standards have lowered the limits for Particulate Matter (PM) mass and Particle Number (PN) emissions requiring further optimization of gasoline direct injection (GDI) engines. Partially burned and unburned lubricating oil contributes significantly to black carbon and soot particle emissions which are not neglectable compared to fuel generated particles. Oil emissions are influenced by engine speed and load conditions but also by engine oil properties and formulation. Minimizing oil consumption has become a fundamental concern and there is a real need for better understanding associated sources and mechanisms. Therefore, researchers and engineers need appropriate tools and methodologies to solve these new problems. A reliable oil consumption measurement methodology able to quantify oil emissions (all oil emissions forms) and only oil emissions is a prerequisite.

New environmental regulations require significant reduction of fuel consumption and engine emissions. This implies improvement of the internal combustion (I.C.) process, reduction of friction, development of complex after-treatment systems, and a reduction of oil consumption. New technical challenges are related to fuel dilution problems in diesel and super-ethanol engines; new wear problems are due to fuel dilution and soot loading in the lubricant; clogging and poisoning problems of after-treatment systems are related to oil consumption, etc. Therefore, researchers and engineers need appropriate tools to better understand and solve these new problems. The paper focuses on the combination of modern engine test beds equipped with innovative radionuclide techniques for real-time oil consumption, oil aeration, fuel dilution, and for on-line wear measurement.

On-line measurement of oil dilution is of particular interest in light of new environmental regulations imposed on today's high-performance engines. In particular, after-treatment devices such as diesel particle filters (DPF) need to be periodically re-generated in order to eliminate their soot content. Such re-generation process is usually performed by using post-injection cycles that can induce a transfer of fuel to the lubricant, resulting in oil dilution. A new method was recently developed by DSi sprl and Total France for monitoring oil dilution on running engines. It is based on lubricant labelling using a new radiotracer compound, which is stable and representative of the oil distillation interval. Measurements are performed by circulating the engine oil to a measuring chamber where dilution is monitored. The method was recently applied to gasoline and diesel engines where dilution results have proven to be accurate and repeatable.

Thin Layer Activation (TLA), a radionuclide technique, was recently applied at the Research Center of ELF Solaize, France, to perform on-line monitoring of wear on diesel car engines. Measurements aimed at better understanding how wear develops on cam lobes as a function of various parameters such as lubricant formulation, soot concentration, and oil aging. The engine itself (passenger car diesel engine) was operated under severe steady state conditions (speed, torque, oil temperature and smoke) and on-line measurements were performed by applying two independent methods: direct measurement of material loss from cam lobes (inlet and exhaust valves) and concentration measurement of worn debris in oil or in the oil filter. These methods have proved to be very repeatable and absolute wear values given by TLA were consistent with those measured by profilometry.

In order to meet the particulate emission targets (6 x 1011 #/km), some gasoline direct injection (GDI) engines might require the use of particulate filters (GPF). The lifetime of wall-flow filters is influenced by the composition of the engine lubricant due to its potential to contribute to the ash accumulation in the GPF. Due to space constraints and to facilitate trapping and soot regeneration, a large number of GPFs will be in closed-coupled configuration. A study was carried out on an endurance test with a radio labelling method and conventional mass gain measurement to evaluate this GPF configuration, and verify the impact of metallic additives contained in the lubricant such as magnesium (Mg) and calcium (Ca) based detergent, a zinc (Zn) based anti-wear, and a molybdenum (Mo) based friction modifier. Two oils were evaluated, with two levels (0.85%-1.1%) of SAPS (Sulphated Ash, Phosphorus and Sulphur).