Disadvantages: only filtered oil in the 60% of impurity filter efficiency is low;
This is because the oil filter, is relying on a single paper filter pores blocked filter out harmful impurities in the oil, the effect of micro-hole filter lower filter is the better, but more oil capacity differential. In order to solve in the same micro-hole filter can filter out the smallest particles of impurities and can supply enough engine oil can pore through this conflict. By the country internal combustion engine industry association filter-branch, ISO4548 oil filter oil filter efficiency test method test showed that even if the oil filter is the best on the market, and can only be designed to remove oil capacity of 60% impurities in, this is the result of thousands of experiments is just the maximum filter value. In practical use, there is 40% of harmful impurities, not paper filters effectively filter, impurities in this 40% due to magnetic impurities are relatively small and hard, so to ferromagnetic impurities, the majority, it is largest for engine damage.
Defects II: filtration efficiency is zero under special conditions;
Existing use of oil filter, in the bottom of the paper filter element is equipped with a by-pass valve, this is in design-time, in order to take into account the cold start of the engine oil viscosity, or paper filter clogged with parts or all of the jam, designed to ensure the smooth circulation of the oil back into the engine oil flow channel directly. Dang oil in pump of pressure Xia open bypass valve Shi, at by bypass valve cycle back engine of oil not only have not to paper filter of filter, and also will will original has was paper filter filter out of big particles impurities, by bypass valve again rushed returned to engine in the, to engine brings not continuous of two times wear, so market Shang using of oil filter device, in special conditions Xia fundamental up to filter role, so at of filter efficiency for zero.
From these two defects are visible, used oil filters, is greater or less than its paper of micro-hole filter impurities up to the permanent filter, only those equivalent to paper filter pore and are lined with paper filter impurities in porous play a permanent role in filtering, filter efficiency is very low.