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A previous experimental work had been carried out in our laboratories to investigate the impact of lubricating oil formulations on deposit accumulation of a continuously regenerating Diesel Particulate Filter. Tests on a passenger car diesel engine were conducted with the use of an accelerated test procedure aimed at enhancing the oil effect on filter weight increase and exhaust gas backpressure. The accelerated test procedure [1], which had proved to be a good tool to discriminate in short time oils having a different impact on DPF performances, was here used to evaluate the behavior of two different types of DPF systems, using oils characterized by different ash content. A slight difference emerged from the comparison between DPF types in terms of accumulated deposits as a function of oil sulfated ash. An experimental section was dedicated to the evaluation of the impact of oils and fuels characterized by different sulfur content.

The present work investigates the impact of lubricating oil formulations on efficiency and durability of Diesel particulate filters (DPF) by means of tests on a passenger car diesel engine retrofitted with a continuously regenerating DPF. An accelerated test procedure, characterized by oil injection into the intake air manifold to simulate a higher oil consumption, was designed and used to enhance the oil effect on trap weight increase and exhaust gas backpressure. Different prototype oils, designed to evaluate the influence of key additives characterized by a different elemental content, were used. The accelerated tests revealed to be a good tool to discriminate, in a short time, oils having a different impact on DPF performances. The main role of oil consumption and oil ash content emerged from the tests.

The present work aims at deepening the phenomenon of oil consumption, paying particular attention to the study of oil consumption contribution deriving from turbocharger. In order to evaluate the quantity of oil that leaks from turbocharger oil seals, it was necessary to design a turbocharger lubricating oil system that is totally independent from the main lubricating circuit. The oil consumption from both turbocharger and engine was measured with gravimetric method. A Mercedes OM364LA medium duty Diesel engine was run at maximum power output for more than 300 hours. Different lubricating oils were alternated in order to evaluate the influence of some lubricating oil parameters on oil consumption, while a reference oil was tested at different times to estimate the oil consumption trend during life for both engine and turbocharger.

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.

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.

The physical characteristics of lubricating oils can affect the mechanical efficiency of internal combustion engines and as a consequence the quantity of fuel consumed at constant power output; moreover they can influence the quantity of lubricating oil drawn through pistons and valves towards the combustion chamber. Exhaust emissions can be influenced both by fuel and oil consumption, so the physical characteristics of the oil can indirectly affect them. The purpose of this experimental work is to study the effect of the physical characteristics of lubricating oils on emissions, fuel economy and oil consumption in a light duty diesel engine. The study was carried out on a VM Turbotronic diesel engine characterized by low exhaust emission levels (1996 European limits for passenger car achieved without catalyst) and high specific power (37 kW/litre).

The purpose of this experimental study was to investigate the relative influence of the physical characteristics of monograde and multigrade lubricants on engine oil consumption, taking into account different engines and different operating conditions. A bench test program on FIAT FIRE 1000 and BMW S14 gasoline engines was carried out using an automatic oil consumption measuring equipment. The interaction between simulated driving conditions (highway, hill-road) and oil consumption was studied using lubricants differing in volatility and rheology: the results showed the importance of volatility in limiting oil consumption; the influence of viscosity was more complex, as it depends on the engine; the role of VII polymers was also pointed out. The hill-road for FIAT and the highway for BMW were identified as the most severe driving conditions.