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Air Filters: Dry vs. Oiled

I remember my shop teacher giving us a lecture about the combustion engine. We were a bunch of know-it-all teenage boys and one plucky gearhead gal, so when he asked what our car’s main fuel was we all responded prematurely: gasoline (or diesel--that gearhead was rocking a dually diesel super heavy, after all). The teacher just shook his head and started waving his hands through the air. “This,” he said, “is your main fuel source.”

Of course, he was referring to the air (well, really the 21%-ish oxygen in our air). While our fuel answer wasn’t wrong exactly, the gasoline and diesel are really just the catalysts. I mention this adolescent high school lesson because it always reminds me of the importance of selecting and maintaining the proper air filter, since a dirty air filter leads to an engine that is underperforming--and I am all about maximizing my performance!

Dry Air Filters

Unless you buy an already modded and souped up ride, you are rocking one of these until you upgrade. These are the typically white, typically cotton filters that come preinstalled in your vehicle these days. And while someone looking to push the most horses out of their turbo-charged dragster wouldn’t be caught dead with one of these, for the common everyday driver, these filters do just fine. They filter out dirt and dust and pollen and keep your engine squeaky clean. Some dry air filters are even reusable. They perform best in dry climates. Regardless, these kinds of air intake filters need to be cleaned/replaced every 10-15k miles.

Do note that while I'm kinda all about that oiled filter, these Dry Air Filters are actually best for dry climates, so if you live in the desert or high plains desert, you may want to stay with these Dry Filters even though Oiled Filters may push you to the next level. The reason is that in drier climates so much dust and debris may limit the Oiled Filters effectiveness by clogging it up just as quickly as the Dry Air Filter would be dirtied. In other words, these styles become more comparable in dry climates, so sticking with the Dry Filter starts to actually make a lot of sense if you are living in a desert region.

Dry air filters are standard, economical, and meet the minimum standards of air filtration for your vehicle. Always be skeptical of that word--”minimum.” Another way of saying that is “we could do better!” So while again for most drivers, this minimum works just fine, for those of us who push our vehicles a little harder or are trying to get that extra burst of speed off the line, we might need an alternative.

The problem with the dry air filter is actually in the design. Particles of dust and debris get trapped in the fibers. So the more it filters out of your air, the dirtier the filter gets, the harder it is to get a strong flow of air into your engine. Install a new dry air filter, drive your car around for an hour, and bingo, you’ve already got a dirty filter. Chances are that filter is still functioning quite well, though it is restricting some air flow. But still--we could do better.

Oiled Air Filters

If you have installed (or are considering purchasing) a cold air intake kit, then chances are you may have an oiled air filter. They are typically reddish to pinkish in color and come with the appropriate amount of oil already applied to them. While efficiency wise, both the oiled and dry air filters are fairly comparable--both filter out nearly the same amount of contaminants, within a percentage or so--oiled air filters are the clear winner when it comes to air flow. Again, the reason has to do with the design. Since dry air filters use tiny gaps in cotton or foam to catch and filter out particles, oiled air filters use--you guessed it!--oil. This allows the gaps in the material and mesh of the filter to be wider, hence more air flow. More air, as my shop teacher so correctly pointed out, means more power! And as more dirt gets stuck in the oil, it doesn’t prevent more air from getting through, as the paper material does. Of course, this has to do with how often you clean and maintain the oiled filter as well. Speaking of...

 Maintaining Your NEW Cold Air Intake Oiled Filter

Now, before you run out and get one of these bad boys installed, let me explain the maintenance. Unless you’ve been dealing with a reusable dry filter, you will be in for a little more effort during regular maintenance once you’ve modded your air filtration system to include an oiled filter. Check the instructions for your system and make sure to clean the filter using the appropriate spray/chemical and to re-apply the correct amount of oil each time you perform regular maintenance checks. I’d like to tell you that it is an old wive’s tale that over oiling can damage your airflow sensor, but I’d be lying to ya. So make sure you follow the instructions correctly. Just like you wouldn’t over tighten your lug nuts, you don’t want to over oil your air filter. If this all sounds like too much work for you, then you might consider sticking with a dry filter. Before you make that decision though, keep in mind that some independent studies of Oiled Filters show that they may allow up to 300% more airflow than dry air filters. And remember: more airflow means higher performance--more horsepower and quicker throttle response time (what my brother calls, “More get-up and go!”).

The Right Filter for You

Your driving conditions, climate, and maintenance schedule/aptitude will help you determine the right air filter for you. Regardless of your choice, here at Midwest Aftermarket we have a number of Cold Air Intake Systems available. Looking for an easy maintenance Dry Air Filter? We’ve got ya covered. Ready to step up to an Oiled Air Filter? We’ve got plenty of those as well.