The Influence of an On Line Oil Recycler on Oil Quality from a Bus in Service Using Synthetic Oil

A method of cleaning lubricating oil on line was investigated using a one micron bypass particulate filter followed by an infra-red heater, to remove water, dissolved gases and light diesel fractions in the oil. The impact of this oil recycler on oil quality was studied using synthetic oil in an on-road bus test. The bus was of Euro-1 emissions standard and equipped with a Cummins 6 cylinder 8.3 litre turbo-charged inter-cooled DI engine. Comparisons tests were undertaken with and without the oil recycler for about 28,000 miles. Oil samples were analysed about every 2000 miles. The results showed that the on line oil recycler achieved significant improvements in the oil quality. With the recycler, the TBN depletion rate was reduced by 52%, the TAN increase rate was reduced by 27% and the carbon accumulation rate in the oil was reduced by 42%. The fuel dilution was reduced by the recycler. There was also a significant reduction in all the wear metals in oil apart from copper, which was influenced by copper components in the recycler. Metal reductions varied from 38% for iron to 100% for aluminium. Accordingly, the oil recycler could extend the lifetime of the synthetic oil by between 37% for TAN to 108% for TBN as the oil life determining factors. The oil recycler also reduced the lubricating oil consumption by 24.5% and reduced the fuel consumption by 3.4% over the test period.