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Everything you need to know about car oil filter

With a perfect circulation of oil in engines, the oil filter is featured to prevent contaminant from the engine oil without interrupting the lubricating process. oil filters are applicable in different types of hydraulic machinery.

The device is used in internal combustion engines both on- and off-road motor vehicles. Great important of oil filters in modern combustion engines that allow first-class lubrication for seamless operation.

types of oil filter

Quality oil filter plays an important role in an engine as it avoids damages caused by dirt particles, soot or unburned fuel in the oil. Today you’ll get to know the definition, functions, parts, types, working principle, diagram, and symptoms of a bad oil filter.

Read: Understanding Engine Lubrication System

Oil Filter Definition:

An oil filter is a mechanical device that removes contaminant, dirt, and unburned fuel from circulating. The component allows just the circulation of fresh oil into the engine and it keeps the dirt. This is why the oil filter needs to be treated or change within some period of time.

an oil filter is equipped on other vehicle hydraulic systems, such as automatic transmissions, and power steering. Gas turbine engines, such as jet also uses oil filter. In short, on the filter is used on a car, truck, motorcycle, boat, aeroplane, tractor, etc. they all use the component for purifying oil and removing dirt from the oil before circulating.

Functions of Oil Filters

Below are the functions oil filters offers:

  • As earlier mentioned, engines provide dirt particles and combustion residues such as dust, metal debris, oil carbons or etc. oil filers collect this particle from the oil before entering the engine. The oil filter cleans the engine oil as consistent engine performance depends on clean oil.
  • Soot gets into the oil, soil and thickening it. Oil filters consist of several thinning holes that avoid thick oil from the pump into the engine.
  • All moving parts such as connecting rods, camshaft and valvetrain are protected from wear and damage if the filter functions well.

Major Parts of Oil Filters

Below are the components inside an oil filter:

Tapping Plate:

A tapping plate is an entry and exit point on the oil filter. It contains small holes around the edge which allows the free flow of oil into the filter container. The threaded hole at the centre is where the oil flows out and it faces the engine.

Antidrainback Valve

The oil filter part is a rubber valve with a flap that holds oil from flowing back into the filter when the engine is not running. The filter required this because it’s located between toward the middle or bottom of an engine.

Filter Medium:

A porous filter medium contains microscopic cellulose fibres and synthetic fibres such as polyester and glass. it helps to increase filtering durability and efficiency. It’s also saturated with resin to offer stiffness and strength. high-performance filters are designed with more synthetic fibres.


The folded filter medium creates a greater total surface area. Well, the number of pleats will be determined by the medium’s thickness.

Center Steel Tube:

This oil filter part provides structure to the filter and allows filtered oil to return to the engine. The number, size, and position of holes will ensure the effectiveness of the oil flow and not being restricted.

Relief Valve:

Because oil can be too thick to filter on a cold start, the engine needs to be prevented from starving. An oil filter is designed with a relief valve that opens when enough pressure is produced to force the calibrated spring downward. This allows unfiltered oil into the centre tube through the top.

End Disc:

An end disc which is made of either fibre or metal is used to stop the unfiltered oil from leaking into the centre tube. This end disc is bonded to each end of the filter medium.


A retainer is a bit of metal that acts as a leaf spring. It keeps the filter medium and end disc tight against the tapping plate.

Below is the complete diagram of an oil filter:

oil filter parts

Read Things you must know about connecting rod

Types of Oil Filters

Below are the major types of oil filter used in automobiles:

Full-Flow Oil Filter:

The full-flow oil filter is the most common type used on cars which are also known as a primary oil filter. It is designed to clean and remove impurities from all the oil used by the engine. Full-flow filters are specially designed to work in colder temperature, cold weather cause motor oil to thicken and at cold start is the oil is thick.

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These filter types allow the oil to move more freely through the engine than other types. If a filter is too restrictive, the engine may be starved with oil which may cause damage to its part. This is why the full-flow filter is better as it provides sufficient oil needed for the efficient performance of the engine.

Cartridge Oil Filter:

The cartridge is a type of full-flow oil filter that is less complex and easy to use. It’s mounted upright which make it easily accessible for inspection without needing to remove the oil. These filter types are available in both metal and fibre but in most cases fibre which makes it easier to recycle.

Spin-On Oil Filter:

A spin-on filter is another type of full-flow oil filter that contains a steel canister with a paper element. Car owners can easily fix it themself since the installation is simple and it requires minimal tools.

Secondary or By-pass Oil Filter:

In some automobiles, secondary oil filters are used to support vehicles with full-flow filters. It’s designed to purify less than 10% of the engine oil. Contaminants there were not removed by a full-flow filter will then be clear-off by the secondary oil filter. These filter types extend the life of motor oil and ensure additional protection to the engine.

Spinner Oil Filter:

A spinner oil is a type of secondary oil filter that uses centrifugal force to trap contaminants from the engine oil. Some of the filters can generate more than 2,000 force, which is greater than that of gravity. These filter types have the possibility of removing tiniest contaminants from the motor oil.

Magnetic Oil Filter:

Just like the spinner oil filter, a magnetic oil filter is also a type of secondary filter that supports the full-flow version. It is designed to effectively remove metallic contaminants from the motor oil but does not clean dust and grime.

Magnetic oil filters don’t need replacement like the other types. All it needs is regular cleaning to keep it functioning.

Working Principle of Oil Filter

The early produce engines did not use oil filters and are even install with poor quality oil, which causes frequent oil changes. When the invention of the first full-flow oil filtration system was developed, the problem was solved. Conventionally, oil flows through the filter before reaching the moving components inside the engine.

The working of oil filters is simple and easy to understand as oil enters the device through a series of small holes on the outer edge base flange. The oil the move through the filter for cleaning which then eventually return into the engine through a larger centre hole.

Most filters nowadays are designed with an anti-drain-back valve, mostly in the form of rubber membrane. This part is often located at the perimeter holes in the base flange. The membrane open as oil enters the filter case under pressure. When the engine is at rest, this membrane closes the holes. The system valves maintain oil within the filter and prevent engine dry stars, that’s for an engine to start with no oil.

Read: Understanding an automobile valvetrain

Modern internal combustion engines are incorporated with a by-pass filter which is known as secondary oil filters. They protect the engine from starvation under some certain situations i.e. in very cold weather that causes oil to be thick, bypass oil filter allows such oil to easily pass through it. Oil can also bypass the filter when the filter is plugged. This is because, oil is sometimes not filtered, even when a full-flow filter is available in the engine.

Watch the video to have more understanding of how oil filter works:

Symptoms of bad and failing oil filter

Bad Engine Performance:

Unlike the working of the engine when an oil filter is in good condition, the performance level of the engine will drop dramatically. One will notice how the engine will hardly pick up speed as it should in normal condition. The accelerator will act like it’s not working properly. Serous care should be taken if any of these symptoms occur or else damage will be cause to the essential part of the vehicle.


Sputtering in a vehicle is related to a clogged oil filter. it happens when the oil filter is unable to release oil as it should be which cause the car not to keep up with the speed you deserve. Light sputtering could lead to a bigger problem.

Metallic Sounds:

A faulty oil filter can cause oil starvation to the engine and when this happen metals will grind against each other. The occurrence of metallic sounds when the engine is running is a sign that something is wrong with the oil flow. Users that experience such sound should ensure fixing it as soon as possible before more damage is done to the vehicle.

Dropping Pressure:

One can read the oil pressure gauge from the vehicle’s dashboard to ensure the pressure is not dropping. Discovering a steep drop in oil pressure is a problem that must be examined. Naturally, engine oil pressure will not drop more than a fraction of a per cent while driving. So, a drastic pressure change is a sign of error in the oil flow.

Dirty Exhaust:

A clogged oil filter causes black or dirty exhaust coming out from your car. Users will often smell oil burning as it passes into the exhaust pipe. This is a sign of a bad filter that needs replacement as soon as possible before more damage will be done.

Read Things you must know about the engines oil pan/sump

In conclusion, we saw the great importance of oil filter in engines which one of them is oil cleansing. We also overlooked more functions, as well as parts and types where we explained the full-flow and by-pass oil filters. We also examined symptoms of bad and failing oil filters.

I hope you enjoyed the reading, if so, kindly comment, share and recommend this site to other technical students. Thanks!

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