A variety of additives are used in automotive diesel fuel to meet specification limits and to enhance quality. For example, lubricity additives and cold flow improvers are used to meet specifications whilst diesel detergents further enhance the quality of the fuel. Recently, several premium fuels that use high levels of diesel detergents and, in some cases, cetane improver have been introduced in the market place.
The purpose of the work carried out was to assess the potential impact of these additives on vehicle performance. In order to do this, a fuel free of any additive was treated with very high levels of all the diesel fuel additives currently used to meet specification limits and to enhance diesel fuel performance.
A common rail vehicle using an advanced common rail system was then driven in a controlled manner for 50.000 km. Emissions and driveability tests took place at 0km to provide baseline data. Further tests were then performed at 15.000km and 50.000km to determine any changes from the baseline data. Moreover, every 5000km the vehicle/engine parameters were assessed via ECU interrogation. Test fuel analyses were carried out every 10.000km, sampling the fuel from the vehicle tank. At the end of the test a full investigation of the fuelling system was undertaken.
The results indicated that the use of the diesel fuel additives at high treat rates did not have any impact on the fuel injection equipment (FIE), the vehicle performance or the fuel itself. This would indicate that high levels, and indeed standard treat rates, of the additive technologies tested are harm free in the field.