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Going With The Flow: How an Engine Oil Filter Works

oil filter

When your car alerts you that it’s time for an oil change, how quickly do you do it? If your answer is that you thought the warning light was just a permanent fixture on your dash, maybe it’s time to do some serious soul-searching. It’s easy enough to put off changing your oil and oil filter, but the damage caused by this negligence can be swift or a long time coming — it will arrive one way or another, though. Knowing how an oil filter works and what it does for your engine might help you gain a better appreciation for the little things that play a big role in keeping your car humming.

Inner Turmoil

The importance of a properly oiled engine cannot be denied. With all the rapidly moving parts working in such precise proximity to one another, oil helps remove heat and ease movement to reduce friction. Too little, too much, incorrectly pressurized or contaminated oil spells quick and expensive trouble for your engine. Oil filters play an integral role in maintaining proper oil quality and supply. Over time, oil takes on tiny particulate matter and minuscule metal shavings from the combustion process. If unchecked, these particles can accumulate and damage the pump, engine bearings and any surface the oil passes under pressure, such as cylinder walls. They can also clog the filter, which puts you in danger of decreased oil pressure and can quickly cause severe engine damage.

Toiling AwayHow an Oil Filter Works

The oil filter works to remove contaminants from engine oil, extending the life of the engine and maintaining high oil quality, which naturally degrades over time. The oil pump sends used oil through a filter element, removing the particles and allowing the oil to pass through. The freshly strained oil is then taken back up to the engine for lubrication. There are different makes and sizes of oil filters, and it’s important to consult your owner’s manual and verify that the replacement will fit. An ill-fitting filter can cause leaks and damage the threads on the engine, which require more intensive repairs. If the oil filter is too big or too loose, it can come off entirely, making a big mess and bigger internal problems.

Spoiled Components

Spin-on oil filters are pretty straightforward, but not all are created equal. They consist of a metal housing, a base plate that matches up to the engine, a sealing gasket to help insure fit and guard against leaks and a filter element. Most oil filters today also come with a bypass valve as a backup in case of a clog. The base plate has one large hole in the middle and several smaller ones surrounding it. The filter element runs lengthwise in a circle, between the big and smaller holes. Oil is forced through the outside holes through the filter, and the engine picks it back up through the main chamber. The bypass valve exists on the boundary between used and filtered oil and opens when the pressure rises enough to indicate a problem with flow. These are the main components, but manufacturers deploy them differently to be more effective or sometimes to cut costs. A lot rides on the materials and internal design; generally, you get what you pay for.

Hopefully, this knowledge inspires you to change that oil filter as recommended.

Check out all the ignition parts & filters available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how an oil filter works, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Blair Lampe View All

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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