Bypass Filters
By-pass oil filtration features a secondary filter with the purpose of eliminating nearly all contaminants in engine oil. They have high capacities and eliminate much smaller particles than full-flow filters, including soot. Bypass filters reduce engine wear and increase oil volume, but their high efficiencies mean they also have higher restriction and must be used in conjunction with a full-flow filter.
Bypass filters operate by filtering oil on a “partial-flow” basis. they draw approximately 10 percent of the oil pump’s capacity at any one time and trap the extremely small, wear-causing contaminants that full-flow filters can’t remove. Bypass filters have a high pressure differential, causing the oil to flow through them very slowly and allowing for the removal of smaller contaminants. It is called bypass filtration because the oil flows from the bypass filter back to the sump and bypasses the engine. This continual process will eventually make all of the oil analytically clean, reduces long-term wear and can extend drain intervals.