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The following article was written by the newest contributor to, Bill Hilton of CAI Inc..

Choosing A Dry Or Oiled Media Filter For Your Vehicle

When choosing an air filter for your vehicle, a very common question is whether a dry media filter (paper filter) or an oiled filter is the best choice. There has been much debate to this subject to determine which filter actually performs better, considering things such as filtration, airflow, longevity and overall performance. Although the debate has been fought from both sides, and both sides may be able to argue pros and cons for each filter type, the filter type that the engineers at Cold Air Inductions Inc. trust and use is the oiled filter.

One of the most common and misunderstood conceptions surrounding oiled filters is that they will cause problems with your MAF sensor. The only time this would ever happen is if when you went to clean and oil your filter (often referred to as recharge) after the recommended time from the manufacturer, you over oiled the filter and/or damaged it and did not let it dry enough. This is no different than if you fill your vehicles engine with too much oil, causing damage to it. As long as the directions are adhered to when using your cleaning kit supplied by the manufacturer, you should have no problems.

When deciding which type of filter would be used with our Cold Air Intakes, many things were considered, researched and tested when choosing between an oiled filter and a dry media (paper) filter. The 3 main requirements that were important to us are the same characteristics that are important to all consumers when choosing an air filter; those 3 items are filtration, air flow and longevity.

Filtration and Airflow
In order for a dry media, paper air filter to filter dirt effectively, the filter and its fibers must be thick and densely compressed in order for them to filtrate up to industry standards. That being said, this denser and thicker media becomes more restrictive, not allowing air to flow as fast and efficiently as it should. Due to this restrictive media, over time, a dry media paper filter will build up with more and more dust and dirt particles.

Once debris has built up to a certain point, the pressure inside the filter will drop while the air pressure outside the filter will remain the same. If the buildup gets too bad, and the difference in pressure becomes too great, it can result in a dry media paper filter to cave in or collapse on itself. In addition, an excessively high difference in pressure between the inside and outside of the filter, brought on by an overly clogged filter media, can literally pull dirt particles through the paper medium. This causes the air flow and filtration to decrease as the filter becomes more and more clogged.

In comparison, oiled filters include multiple layers of oiled cotton or gauze fabric which captures dirt and debris more effectively. The debris entering the filter will actually stick to the oiled fibers of the filter, and actually become part of the filtering media. This process, sometimes referred to as depth loading by some filter manufacturers, allows the filter to retain more dirt per square inch than a paper filter. On many oiled filters, the cotton or gauze fabric is then meshed between pleated aluminum screens. Pleating the layers of filter media increases the surface area which allows the filter to be in use longer, and capture more debris than a standard non oiled and/or non-pleated filter media.

As dust particles enter the filter they are stopped by the interwoven layers and are then captured in place through the oil. Dirt and debris that are retained on the surface of an oiled filter media have little effect on air flow because there are no small holes to clog like there would be on a paper filter media due to the interwoven layers. So when a paper filter starts to clog, an oiled filter media is still filtering debris just as effectively as when you purchased it, as well as retaining a higher level of airflow. This is due largely to the oiled filter media as well as the method that is used to hold the layers together.

When tested, we have found that an oiled filter media will have less restricted flow when compared to a dry media paper filter on a flow bench test. Although an oiled filter media may have between 4 and 8 layers of filtration, it still flows faster and less restricted than a paper filter that is densely bound together. So while filtration is increased, the flow is also increased because of the manner in which the filter layers are constructed.

Another great reason to choose an oiled filter over a dry paper filter is for the longevity and cost savings it will provide you. On average, a paper filter should be replaced between 4,000 to 5,000 miles or every oil change. Typically the average cost of a paper filter is about $10 to $12. After one year of driving 15,000 miles, at least 3 paper filters are needed, this totals $30 to $35. An oiled filter will generally run from $25 to $50, but will never need to be replaced! Therefore an oiled filter will “pay itself off” so to speak in 1-2 years. As long as you plan on driving for more than another 2 years, your costs saving over the life of the vehicle will greatly add up, especially if you are paying for the labor to replace the filter at your dealer or local auto shop. Considering the fact that you may only need to “recharge” your oiled filter a few times during the course of its service life, and that It will never need to be replaced, it makes vehicle maintenance simpler and more affordable.

For the reasons above as well as others, Cold Air Inductions prefers the benefits of an oiled filter media as opposed to a dry paper air filter. For more information and a 3d look into Cold Air Inductions Inc. specially designed and engineered high performance air filters, please visit Cold Air Inductions Inc. - Cold Air Intake Systems - High Performance Cold Air Intakes & Filters I hope that you have found this information helpful, and look forward to bringing you more informative articles soon!
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