While oil is primarily used to lubricate and cool moving parts of an engine, it also transfers harmful abrasive particles to the sump. these particles must be removed before the oil can circulate around the lubrication system again. An efficient way of removing these particles preventing unnecessary wear or damage, is to pass the oil through a filter before it reaches any of the critical moving parts.

The filter must be designed to allow large quantities of oil, at high temperatures, to pass through it and remove the harmful abrasive particles of carbon, metal, silicates, wear debris etc. While the continuous flow of oil through the filter keeps it in a clean condition, it is important that the manufacturer's recommended filter change intervals are observed, in order to maximize engine life.