Over time an oil filter can collect enough contaminants to become restricted. The engine can sense that the filter is blocked by the pressure differential between the oil going into the filter and the oil going out. If the difference in pressure is great enough, the engine will bypass the filter media to keep the oil pressure and starving the bearings for oil. When a system is in bypass, contaminants are not being filtered out of the oil. This is fine if the oil is cold during start-up. Over a longer period of time, however, wear can be rapidly accelerated. In this video, Andrew Markel makes the connection between oil change intervals and oil filter replacement. This video is sponsored by FRAM.