Enhancement of engine lifetime with premium fuel

In order to evaluate the impact of premium fuels containing elevated levels of friction modifier (FM) additives regarding wear, engine test bench investigations were performed with a conventional fuel and with a premium fuel containing FM. All tests utilised an artificially aged engine oil that simulated the condition of a reference used oil after 25,000 km of operation. Thus, a large-scale artificial ageing of 180 L engine oil was carried out with oil condition monitoring by means of conventional parameters and high-resolution mass spectrometry. Oil analysis confirmed a comparable condition of the artificially aged oil with the reference used oil. Additionally, SRV® tribometer experiments with the artificially aged oil proved a significantly higher coefficient of friction compared to the fresh oil but similar tribological performance compared to the reference used oil. During the engine bench tests, wear was monitored via wear particle concentration in the oil by means of optical emission spectroscopy as well as by radio isotope concentration method with activated piston rings. Both analytical methods found a significantly lower wear in the engine bench test operated with premium fuel with FM compared to tests with conventional fuel. Moreover, subsequent used oil analysis from bench test oil samples by mass spectrometry showed a transfer of the FM from the fuel into the engine oil. In particular, an increase in FM with proceeding engine operation time was observed. Hence, the usage of premium fuels may lead to enhanced engine lifetime.