In Depth Analysis of Engine Oil Filter

We can call the analysis of engine oil filters “Oil Filter Anatomy” to familiarise ourselves with the machinery lubrication. Here, we will be examining the engine oil filter particularly to know more about its characteristics regarding performance and functional aspects. In addition, other addition, other pics related to the oil filter analysis will also be discussed, including the best practice for using the oil filter, correct filter selection factors, possible failure modes for the filter, and the maintenance of an installed filter.

A Brief Intro To The Engine Oil Filter

An oil filter is a component that mainly cleanses the oil from dangerous contaminants in a machine like an engine, hydraulic system, transmission, and other systems run by oil. It was 1922 when the oil filter was invented and used for automobiles. At that time, it was called the Purolator, which means ‘Pure Oil Later.’ After that, the evolution continued until the 50s, when we got the modern spin-on filters that the automotive industry use nowadays. Among all the oil filters, the canister-type filters became very popular. The configuration of this filter made a big boost in the performance of the oil filtration system.

It’s not the automotive industry alone where the engine oil filters have become integral parts. They have become very important to industries like aerospace, oil refining, power generation, mining, manufacturing, etc. The canister/cartridge design is the most common for used oil filters. However, many variations are available in filter media, size, flow arrangements, and dirt-impeding capacity.

And there, you need our help to be properly guided in choosing the right filters that meet your application’s needs, considering the performance, cost, ease of use, and other environmental conditions.

Types of Engine Oil Filter

Bosch Workshop Engine Oil Filter
Bosch 72209WS / F00E369846 Workshop Engine Oil Filter

The oil filters are distinguished by filtering the contaminants or by which oil flows into the housing. Surface-type media is the standard technique for controlling the contamination in oil filters. This type of filter is used in the automobile industry. However, the depth-type filters have filter media designed to contain a much higher level of contamination. Therefore, it provides a more complex path for the contaminants to get trapped.

There are a few other contamination methods; one is magnetic filtration, and the other is centrifugal filtration. The magnetic one uses rare-earth magnets/electromagnets to catch ferrous particles when the oil moves through the magnetic flux area. Centrifugal filtration integrates a quickly rotating cylinder that produces centrifugal force to separate contaminants from the oil.

Another way to categorize the oil filters is by the oil flow design. The full-flow filter draws all the oil using the filter media in this design. At the same time, the bypass filter requires only a fraction of the total oil flow to keep the sufficient flow rate in the system. The best design option is determined based on the application’s contamination control specifications and oil flow. There is another option known as the duplex filter system that has two filters set up side-by-side in parallel, allowing one of these filters to be substituted while the operation is uninterrupted.

Generally, canister-type filters allow the standard flow of oil to move from the outside to the inside, meaning the oil travels via the cylindrical filter from the outer facing surface into its inner core. While in some cases, you will find the flow direction is exactly the opposite, where the oil comes into the filter via the core, which later gets pushed outside via the pleat design. With such a design, the distribution and flow handling are improved, and the filter element’s size gets reduced.

Air filter oil or engine oil air filter is another popular filter oil option. It can infiltrate the foam cells and evaporate after leaving sticky residuals to catch foreign particles. 

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Product prices and availability are accurate as of the date/time indicated below and are subject to change. Any price and availability information displayed at the time of purchase will apply to the purchase of this product.

The Mechanisms of Filtration

The filter primarily removes and retains contaminants as the oil flows via the penetrable component named the media. This component operates by undergoing different sorts of filtration mechanisms such as:

Direct Interference and Depth Capture: Particles are blocked on the media as they are larger than the taken sections.

Adsorption is the molecular or electrostatic attraction of the particles between the media and the particles.

The Inertial Impaction: The particles impact the filter media because of the inertia the adsorption holds while the oil flows around.

The Brownian Movement: The particles smaller than one micron are moved by this movement irrespective of the fluid flow. This results in the adsorption of the particles by media within very close proximity. This is less likely, especially in the case of viscous fluid.

The Gravitation Effects: These effects allow comparatively larger particles to stay away from the low fluid flow regions.

In addition, filter media can be designed to capture particles through two distinct methods:


Surface Retention – The media surface holds the contaminants. As a result, the contaminants get trapped when they come in contact with the surface of the media. 

Depth Retention – The media surface and the passage labyrinth within the depth of the filter media hold the contaminants. This way, multiple opportunities are created to trap the contaminants.

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Types of Filter Media

Retaining the captured particles by the filter depends largely on the filter media’s porosity. This is called dirt-holding capacity. Maintaining the low differential pressure across the filter media increases the pore density. In contrast, its pore size decreases, which keeps the oil volume in touch with the surface. The size and depth of the filter also influence the capacity of dirt-holding. The other factor is the material/type of filter media. Filter media is primarily available in 3 different types.

Cellulose: This media type is made of wood pulp with long fibers and inconsistent pore size.

Fiberglass/Synthetic: Made up of smaller artificial glass fibers with pretty consistent pore size.

Composite: This one is a combination of fiberglass material and cellulose.

If we have a comparative discussion for these three, we would say the cellulose media have an advantage over the other two as it can absorb water contamination. But this media has shortcomings, too, as it tends to fail more often than synthetic media in harsh conditions, especially in acidic conditions. Nonetheless, the main reason to prefer synthetic filter media is their smaller fiber size and consistent porosity, providing better longevity and higher dirt-holding capacity.

The Beta Rating

To rate the oil filters, there is a technique known as the beta rating. You can get a detailed explanation of this in the machinery lubrication article “Understanding Filter Efficiency and Beta Ratios” by Jeremy Wright. Here we’ll give a brief idea about this parameter. The beta rating is calculated using a formula where the number of particles bigger than a particular size upstream of the filter is divided by the number of particles of the same size downstream of that filter. Filters have different beta ratios for specific particle size limits like 2, 5, and 10 microns.


A02 Engine Oil Filter
Acura / Honda OEM Genuine 15400-PLM-A02 Engine Oil Filter + Drain Washers – Set of 6
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Product prices and availability are accurate as of the date/time indicated below and are subject to change. Any price and availability information displayed at the time of purchase will apply to the purchase of this product.

Engine Oil Filter Usage: Best Practices

Storage: If the filters are not stored properly,  they can fail before they are used. So its proper storage and handling are very important. Someone must ensure that the filters are clean, dry, and cool. They must also follow the first-in/ first-out formula to avoid any hazards.

Installation:  Installing a filter may seem to be simple and regular routine work if the recommendations and proper procedures are followed given by the manufacturer. However, there is a common mistake that is often seen in this case is the over-tightening issue. Generally, the three-quarter turn after seal contact is considered to be optimal. The effectiveness and longevity of the seal can be inhibited by over or under-tightening. In addition, someone must ensure appropriate fitting of the connections, ducts, and seals and that they are free of contaminants.

Avoid Pre-fill: Generally, filters are not pre-filled before installation. However, a pre-fill is recommended in the case of diesel engines as installing a pre-lube system can avoid changes from the dry-start condition.

Correct Selection: Choosing the correct filter is a challenging job. You cannot determine if any particular filter is correct only because it fits. You can have a wrong one that still fits as filters and housings are designed interchangeably, which can confuse you. So it would help if you were sure that the filter was replaced with the correct one. You cannot rely on the current filter either, as the current one might be a wrong replacement made during the last change.

Training: Changing the filters need proper training personnel involved in the procedure. Untrained personnel may not do it as they should and make a great mess. Therefore, the property should provide proper training for all personnel who will change engine oil or the filter. The filter removal is also a sophisticated task that needs the proper training to use the oil filter removal tools like the engine oil filter wrench.

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Failure Modes Of An Engine Oil Filter

Channeling: When the differential pressure is high,  the filter media passage may expand to the point where the unfiltered oil may go through without any efficient contaminant trap. Additionally, particles contained previously in the filter in line with that expanded passage might get to be set free.

Fatigue Cracks: In the case of the cyclic flow condition, they may form cracks within the filter media. This will allow a breach of oil to get through the unfiltered.

Media Migration: The media fibers may degenerate and create different contaminants from different filter materials. It happens when the filter housing is improperly placed or any inadequate fitting of the oil filter is done. As a result, damaging vibrations may be generated. In addition, incompatible oils and very high differential pressures create embrittlement, resulting in media disintegration.

Plugging: While the machine is Operating, the filter media may exceed the dirt holding capacity and get fully plugged. Premature plugging can also occur in extreme moisture, oxidative products such as sludge, or coolant.

According to some surveys, most lubrication professionals find filter plugging the most frequent failure mode in the engine oil filter.

Factors To Consider While Choosing The Right Engine Oil Filter

Bosch Workshop Engine Oil Filter
Bosch 72209WS / F00E369846 Workshop Engine Oil Filter

Structural Integrity: The structural integrity of the oil filter is the most important factor to consider. This means the filter’s ability to prevent the oil passage through the unfiltered flow path. However, there are standard procedures set up by the International Organization for Standardization (ISO) to test material compatibility, fabrication integrity, flow fatigue, and end load. During the oil filter test, you will know if there is any defect in the media in high-flow conditions regarding the improper sealing of seams and the end caps or breaks. It also reveals the impact of high temperatures on different filter elements.

Dirt-Holding Capacity: This factor refers to the number of contaminants loaded onto the oil filter before the filter’s efficiency becomes limited.

Pressure Loss indicates the complete differential pressure loss from the machine’s oil filter placement. The surface area and porosity of the filter media influence the pressure loss.

Particle Catching Efficiency: This factor is the total effectiveness of the oil filtration mechanism in a filter media that removes and holds contaminants from the oil.

Environment: Finally, the characteristics of the environment and overall system of the machine where the engine oil filter is installed need to be considered, such as the flow rate, contamination expectation, vibration, location, etc.

Maintainance of the Installed Engine Oil Filter

Avoiding the machine’s contaminants from the beginning is the best way to stop the filters’ dirt-holding capacity from reaching its limit. As you see, particles generate particles, so the fewer the ingression of the external contaminants, the fewer internal contaminants are generated. For this reason, there are a few guidelines that we should follow for the maintenance of the installed filters:

  • The first thing is to ensure that the correct breathers have been installed to prevent moisture and external contaminants from entering the machine. 
  • Another important thing is to use the right wipers and boots to keep the seals and the cylinders dry and clean.
  • Finally, selecting the right oil grade and the additive package is a vital issue as it will counter the internal friction by preventing contaminant ingression.
Image Source: K&N

The Engine Oil Filter Analysis

The engine oil filter traps different unwanted particles and concentrates clues to get a picture of what’s happening inside the machine. The practical oil analysis can be challenging as the particles could be highly diluted in the machine. However, you can also visualize the trapped particles with the naked eye as they may be pretty plentiful in the filter.

The metal contaminants determine the primary sign of any issue in a machine. However, a reasonable quantity of metal contaminants is considered normal. Still, any unusual amount can be alarming and need attention by trending the visual appearance of the filter after an oil change program. One easy way to distinguish them is to cut open the oil filter and suspend a powerful magnet over it. This will aid in pulling out these metal contaminants.

You should not discard the filter whenever any machine is suspected of having issues. Otherwise, you will miss out on some key evidence shreds. We should maintain the filter in the same condition as during the removal. Finally, we should take it to the manufacturer or lab for regular analysis.

Image Source: Mechanic Base

Engine Oil Filter Disposal

The engine oil filter’s design is unsuitable for dumping into the wastebasket. The filter disposal procedure is strictly controlled by the increased regulations of the Environmental Protection Agency. Although requirements do vary for each type of oil filter, some common practices are also there that include filter incinerating or crushing, oil draining, etc. Therefore, you can have your used oil filter disposed of at low or no cost at different filter distribution centers or disposal services. 

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This guide is prepared with the right technicalities to give you a proper idea about the engine oil filter so that you can choose the correct one for your machine or vehicle. Most oil filters look very similar; however, you can point out the little differences to get to the right one if you have thoroughly gone through our guide. The best way to determine your desired oil filter is by consulting the user manual or referencing the parts catalog.

Generally, you get what you pay for. Some low-cost filters available in the market contain a cheap composition like light-gauge metal, poor gaskets, and loose filter material, which can lead to the failure of the oil filter. Such aspects as performance and longevity should be prioritized over the filter’s price when buying the best oil filter for your vehicle.

Product prices and availability are accurate as of the date/time indicated below and are subject to change. Any price and availability information displayed at the time of purchase will apply to the purchase of this product.

Mia A Chloe
Author: Mia A Chloe

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