What Really Makes An Oil Filter Effective?

Hint…It Doesn’t Make for Great Video.

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Recently online videos have aimed to compare oil filters by cutting them open, exposing materials and designs and making claims to how that may impact filter effectiveness. 

While that makes for great video, it leads to assumptions that are not accurate nor based in fact.

FRAM has been a top manufacturer of oil filters for more than 85 years, and we have studies, lab tests, road tests and various professional proof points regarding what intricacies of oil filter engineering, production and materials are most effective. 

If you want to ensure that your filter is effective in protecting your engine, consider the following information that provides a different look inside as to what makes for a quality filter.

What Are the Independent Standards for Filtration Effectiveness?

ISO 4548-12 and SAE HS806 test standards are used by oil filter and Original Equipment (OE) vehicle manufacturers. These test standards specify over 15 different procedures to determine the performance and durability of an oil filter. 


Efficiency is a measure of how well the filter removes dirt from the oil. For example, if you had 10 grams of dirt in your oil and ran it through the filter and had one gram left after that, you would say the filter is 90% efficient. However, that simple calculation does not consider dirt particle size. Be aware that by manipulating the size of dirt particles used in testing, nearly any filter can claim over 90% efficiency. The key is to look for a filter that tests at the industry standard using particles at 20 microns using the ISO 4548-12 test. Particles in the 10-20 micron range cause the most damage and wear to an engine.

FRAM Extra Guard® is 95.7% efficient @ 20 microns using the ISO test.

Filter Media Area

Simple assumptions that more is better do not take into account the type of material and design used in a filter’s media area.  In over 85 years as leaders in the oil filter category, FRAM has dedicated significant resources to engineering the best cellulose and synthetic glass microfiber filter media that allows for fewer pleats for the same or better capacity and efficiency, promoting good oil flow. Other filters may use plain cellulose media with more pleats and length, but more is not better.


Capacity is a filter’s ability to trap and hold dirt until the next oil change. This is measured in grams but to aid consumers most, filter manufactures recommend oil change intervals based on the filter model.  Capacity measurements are most relevant to the recommended change interval, which also depends on other materials in the filter such as rubber components. 

FRAM Extra Guard® is rated for the Original Equipment (OE) recommended change interval, meaning it has the capacity to be used for as long as the factory oil change interval stated by the car manufacturer, and is good for use with all oil types and can provide up to 10,000 mile protection

End Caps

The purpose of the end cap is to seal the ends of the filter media.  It can be constructed from engineered fiber, fleece, plastic or steel; some filters have no end cap with just woven ends, and, others use just potted glue. If the material effectively seals the end of the media cartridge, the filter functions as is intended.  The end cap does not have a function in the actual filtering of the oil. 

End caps in the FRAM Extra Guard® and FRAM Tough Guard® filters are constructed from engineered fiber. FRAM has manufactured over two billion filters this way because with the plastiol glue this material allows for a superior seal with the filter media than does steel.

Honda, Subaru, Bentley, Roll Royce and Nissan all use fiber end caps in OE filters. BMW, Mercedes, Porsche, GM and many others use only fleece for an end cap, and Toyota weaves the ends of the filter media together and uses no end cap at all.

Anti-drain Back Valves

The anti-drain back valve (ADBV) is a circular rubber valve at the oil filter entrance, and it opens when the engine is started and closes when shut off. It keeps the engine galleys and filter full of oil, helping assure full lubrication at start-up.  There are two types of ADBVs in the industry - nitrile rubber and silicone.    A Silicone Rubber anti-drainback valve has over 3x the life of a Nitrile anti-drainback valve.  FRAM uses a silicone ADBV on FRAM Tough Guard and FRAM Ultra filters, and switched to a silicone ADBV on Extra Guard filters in 2018 because of its superior performance.

Can Thickness

The thickness of a filter’s metal exterior is irrelevant if the can meets or exceeds the pressure requirements when tested per ISO and SAE test standards. The FRAM Extra Guard, Tough Guard and Ultra Synthetic filters can take over 300 psi burst strength, more than three times the oil pressure a vehicle’s engine could ever develop.  While some filter makers use very heavy steel for their filter can, they do it for the illusion that weight is a measure of filtration quality. Metal material and weight is only relevant for racing oil filters, as these must be able to sustain burst strength up to 500 psi - far beyond any normal driving situations.

Leaf Springs vs. Coil Springs

A leaf spring design is superior to a coil spring design because coil springs place all the stress on the dome end of the filter can which is its weakest part; whereas the leaf spring design places stress on the circumference of the can, its strongest part.

For more information from reputable resources about oil filter quality, please visit:

Oil filter testing and engineering https://www.youtube.com/watch?v=cttLaWepdL0

Oil filter anatomy https://www.youtube.com/watch?v=JSC9KZGDRDk

Cartridge filters/Service bulletins https://www.youtube.com/watch?v=TUnd3DBtivE&t=31s

FRAM Extra Guard Filter Diagram