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A small 0.220 litre Petter IDI single cylinder engine was investigated over a 120 hour test period, consisting of 40 three hour test runs, with emission measurements and lubricating oil analysis every 20 hours for the same batch of fuel and lubrication oil. The particulates were analysed for the SOF and for the fuel/lubricant proportion using TGA. Fuel dilution of the lubricating oil was shown to increase uniformly with time and reached 10% after 120 hours, there was an associated decrease in the viscosity and increase in the lube oil fraction in the particulate SOF. Carbon contamination of the lubricating oil increased to 1.6% by mass over the 120 hour test period. The particulate emissions decreased initially and then increased after 50 hours, but the effect was no more than a 30% variation, mainly caused by variations in the carbon emissions. The motoring particulates were found to be low and dominated by vaporised lubricating oil.

The relationship between a diesel engine lubricating oil consumption and the particulate volatile unburnt lube oil emissions depends on the combustion efficiency of the lube oil in the engine. Very little data exists on this topic and this is reviewed. An experimental procedure for the determination of lubricating oil consumption from a calcium mass balance between the lubricating oil and particulate was used combined with a thermogravimetric analysis of the particulate to obtain the unburnt lube oil emissions, together these techniques enabled the lube oil combustion efficiency to be determined This technique only requires the particulate filter paper as an experimental measurement in the engine test. Initial results for a Perkins 4-236 NA DI diesel engine are presented for a range of loads and speeds.

Diesel engine exhaust pipe and incylinder deposits were analysed for the global fuel, lube oil, carbon and ash fractions for a range of diesel engines. A large SOF fraction, typically 30%, was found and this was dominated by lubricating oil. These deposits are shown to contain significant levels of PAH and hence provide a source of diesel PAH emissions and possible sites for incylinder pyrosynthesis of high molecular weight PAH. A Perkins 4-236 NA DI was used to investigate the role of exhaust pipe deposits on PAH emissions. It was shown that PAH compounds could be volatilised from the exhaust pipe. The difference in the exhaust inlet and outlet particulate composition for diesel and kerosene fuels was used to quantify the n-alkane and PAH emissions originating from the exhaust pipe deposits. Comparison with pure PAH free fuels showed that the exhaust outlet PAH composition was similar to that expected from the exhaust pipe deposits.

The use of two or three FID hydrocarbon analysers for the determination of condensable or liquid unburned fuel is described. Each FID has upstream pumps and filters in separate sample conditioning systems operating at three different temperatures of 180C, 50C and 2C. The 50C system could operate at any temperature up to 100C, the use of 50C was because this was the temperature used for sampling diesel particulates. The difference in the three hydrocarbon readings was used to determined on a mass basis the condensable UHC over the sample temperature difference of either 180C to 2C or 180C to 50C. The latter hydrocarbon difference was shown to be close to the particulate fuel fraction of the SOF. A range of applications of this technique to both diesel and spark ignition engines are described, including the warm-up of a Ford CVH SI engine and the influence of nozzle sac volume on condensable hydrocarbon emissions in a Perkins 4-236 diesel.