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This experimental work investigates the possibility of reducing the lubricating oil impact on diesel exhaust emissions, particularly concerning the particulate matter, by means of a three-stage experimentation on a Hydra Diesel research engine. The influence of the physical characteristics of the oil was evaluated in the first stage. The results showed that the use of low viscosity oils leads to a better mechanical efficiency and a lower specific fuel consumption than high viscosity oils in the examined viscosity range. Emission tests at a high constant load showed a higher Air Fuel Ratio (AFR) for low viscosity oils compared to high viscosity ones, due to a lesser fuel consumption. As CO, Particulate emissions and smoke are greatly affected by AFR at high load, a decrease of these emissions occurs moving towards low viscosity oils. The influence of the chemical characteristics of the oil was evaluated in the second stage.

Deuterated n-paraffins and polyaromatic compounds were added to a reference oil to elucidate its role on the emission of Soluble Organic Compound at diesel exhaust. This work carries on from previous investigations applied to fuel doping with deuterated compounds [1]. Both direct emissions and indirect effects, due to dilution with fuel components and combustion products are investigated. Furthermore the addition of deuterated compounds, is applied to calculate unburned percentage, to study the metabolism of lube oil component and can be applied to measure lube oil consumption. In this paper the results obtained on a light duty and a heavy duty vehicle fuelled with a reference fuel are presented. Particular attention was paid to total particulate and semi volatile phases.

The present work, carried out within the framework of the JOULE-3 European joint project entitled “Fuel and lubricant formulations for high de-polluted engines”, investigates the effect of both the fuel and the lubricating oil quality on deposits, wear and exhaust emissions in the presence of a high EGR rate, with specific attention to the emission variation during aging. Two fuels (a current Italian typical fuel and a Swedish high quality fuel) and two lubricants (a traditional mineral oil SAE 15W-40/ACEA B2 and a full synthetic SAE 0W-40/ACEA B3) were used to carry out six tests, each one characterized by 126-hour duration at different running conditions, on a VM Turbotronic Diesel engine. The engine evaluation pointed out an interaction between oil and fuel: if the high quality fuel (nearly zero S) is used, a low level of cylinder bore polishing and top ring wear, weakly affected by the oil quality, occurs.