An oil filter is designed to keep small particles of dirt, grime and bits of metal from circulating throughout an engine’s oil passages, where they could possibly cause clogs and starve certain areas of the engine from being properly lubricated. This dirt can also do other kinds of damage to cylinder walls and the engine’s reciprocating assembly.
How does an oil filter work? Most oil filters are made of many layers of paper, which work to trap larger particles of matter found in engine oil. These filters come in two varieties – one which is designed to drop into a special compartment in the engine, and one which screws on to the side of an engine. In both cases, all of the oil in the engine eventually has to move through the filter as it gets circulated by the oil pump.
Over time, an oil filter becomes clogged with sludge, dirt, and metal shavings. Once this occurs, it can actually start to impede oil flow in the engine, and it also no longer performs any useful filtration. Generally speaking, an oil filter should be replaced every time an engine’s oil is changed. This is partly due to the fact that it is at the end of its useful service life, and partly due to the fact that the filter is soaked in a decent amount of oil, and leaving it in while replacing the old engine oil would allow a significant amount of old oil to remain in the engine to mix with the new lubricant.
