Search Results

Due to the increasingly stringent emissions standards in the world and, on the other hand, the foreseen shortage of fossil fuels, the application of low viscosity engine oils (LVO) is considered one of the most interesting options for counter these threats. In parallel to a fuel consumption fleet test, the aim of this study was to assess the performance of commercial low viscosity oils regarding their degradation and engine wear, since the use of LVO could imply an increase in wear rate. Potential higher engine wear could result in a reduction in the expected engine life cycle, obviously is a non-desired effect. In addition, currently limited data are available regarding “real-world” performance of LVO in a real service fleet.

This paper shows the results of a fuel consumption in-use comparison test where the effect of Low Viscosity Oils (LVO) was evaluated over a sample of 39 urban buses powered by Diesel and CNG engines. The aim of the test was to verify the fuel consumption benefits of LVO in Heavy Duty Vehicles (HDV) found in previous works, which were obtained mainly in engine test bench, when engines are working on “on-Road” conditions. In order to achieve this goal, a sample of 39 urban buses was studied over an Oil Drain Interval or 30.000 km (approximately an 11 month period), measuring daily mileage and fuel consumed to calculate each bus fuel consumption. Mileage was measured by GPS and fuel consumed was measured from refueling system. The sample was divided into two groups; a control group of buses using reference oils (SAE grade viscosities of 15W-40 and 10W-40) and a candidate group using LVO oils (SAE grade viscosities 5W-30).

Compressed natural gas (CNG) is a promising alternative fuel due to several main reasons, specially the strict engine emission regulations all over the world. This has made that lot's of cities have decided to use CNG as an alternative fuel in their urban transport fleets or in other urban tasks. Nevertheless, due to the recent implementation of the CNG technology in automotive sector, several problems related to lubrication have been detected, mostly affecting a reduction of the oil drain period and these problems showed no relationship with a particular fleet nor with the lubricant's brand used. These effects will have a very important weight on fleet manager's decision to select CNG as an alternative fuel, thus this reduction does not only increase the cost in engine oil, there are other maintenance actions referred to this basic period of oil drain, thus also increases other more significant costs.

Biodiesel blends are promising alternatives to diesel fuel, but, reduced quantitative information is available on the impact of biodiesel on engine systems behaviour, durability and economical aspects in fleet cost management. A representative sample of urban buses fuelled with B50 was compared with the same type of vehicle fuelled with conventional petroleum fuel. The objective was to assess the effects of B50 upon important parameters such as: fuel consumption, power loss and drivability; the effects on the fuel system and engine oil and the implications regarding the maintenance programme. These implications could be very relevant upon a fleet manager's decision to select biodiesel as an alternative fuel. The results obtained show that there was no difference in the serviceability of the buses fuelled with B50 compared with those fuelled with petroleum diesel fuel, and additionally, no change in the maintenance programme was required for this type of B50 fuel.

This paper is structured into two different parts: Firstly, it describes a methodology to evaluate wear conditions in internal combustion engines in order to go beyond the classical evaluation based on specified wear concentration limits provided by engine manufacturers or commercial oil laboratories. The proposed methodology uses spectrometric wear debris measurement data and typical maintenance data to obtain a more representative parameter of wear condition, defined as “compensated wear rate”, that takes into account particular engine operating conditions affecting wear concentration measurements. Later, an evaluation of this compensated wear rate is carried out using statistical criteria and considering individual engine characteristics such as engine age, type of service, engine metallurgy, environmental conditions of work etc.

This paper presents a study and review of the data collected in an Engine Fault Diagnosis System using oil analysis, used for diagnose different industrial vehicle engines (trucks, buses, road construction equipment, etc.). This system is being used since the beginning of the 1990s decade. The information acquired in this system has generated an important database that collects the information about the oil status at drain moment and further collateral information. Knowledge about oil properties (viscosity, TBN, detergency), and oil contamination, (insolubles content, soot from combustion, fuel dilution, and water) during engine operation, provide an important information about lubricants efficiency, optimal drain period and engine status that it has a direct influence on vehicles running cost. The study has been performed with a statistical tool which allows the characterisation of the main parameters of oil behaviour, in addition to the relationship between them.