By-Pass oil filtration works on a partial flow basis adding a secondary filter in conjunction with a full-flow filter to eliminate contaminants in which engine oil leaves behind. The filtration system has high capacities and eliminates smaller particles than what full-flow filters can, including soot and sludge. Before installing, make sure to measure your vehicle engine compartment for enough room. While extending drain intervals, reducing long-term wear, and keeping the oil cooler, By-Pass filters significantly extend engine life and increase engine efficiency. AMSOIL recommends using oil analysis when extending oil drain intervals.