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Do I really need to change my car’s air filter?

“How often should you change your air filter?”

“What is a cabin air filter?” “Do I even need to change it?”

These are frequently asked questions when it comes to vehicle maintenance. Let’s start with the “engine air filter” of your vehicle. First off, is it important that I change it? The answer is YES, and here is why: Your engine operates on a mixture of gasoline (or diesel) fuel and air. On a modern car, and by modern, we’re talking late 1990’s and newer, there is a computer which monitors the air/fuel mixture and makes continual adjustments in the fuel delivery system in order to get it just right, as well as continually adjusting the other engine systems to make up for when that mixture misses the mark a bit. The proper operation of your engine is relying on enough air being able to move through the air intake system, through the air filter, and into the fuel delivery system. If your air filter is dirty, it can restrict the free flow of air into the engine, contributing to lower gas mileage, rough running, and can even generate a check engine light if it gets dirty enough. That is a bundle of potential trouble, all in the effort to save a few dollars by stretching the life of a dirty air filter. That just does not make sense, and it ends up costing you more money, time and trouble – not worth it!

So we have established that you should keep on schedule for changing your air filter, now let’s see where these air filters can be found.
It is not surprising that many car owners do not know about what the engine air filter does, or even where it can be found. On today’s typical car or truck, air filters can be shaped like a square, a rectangle, or some other trapezoidal shape, unlike the old days when they were a thin circular shape sitting prominently on top of the engine. The old style round air filter was the first thing you would see upon opening the hood of a car. It was easily found, and cheap and easy to replace. In the past, you could unfasten one wing nut, lift off the cover, pop in a new filter, and you’re done!

Round Engine Air Filter
Round Engine Air Filter
under the hood-old school
Under the Hood – Old School

On most modern cars and trucks today, the air filter is located within a plastic box-like structure which may even be covered up by another plastic engine cover or other vehicle parts, making identification and changing a more involved process. Look at this modern engine bay:

stock engine airbox and filter Jeep
Stock Engine Airbox and Filter Jeep

Even worse, here is the engine bay of a 2016 Porsche 911 (991). Can you find the air filters? There are 2 of them!

Porsche 991 engine bay
Porsche 991 Engine Bay

Don’t feel bad if you can’t see them, you need to REMOVE THE REAR BUMPER to access the twin air filters! Seriously!

991 air filter change
991 Air Filter Change

Once we actually get to the engine air filters, here are some pictures for you to compare a used, dirty filter with a new and fresh one. You can see how dirty and restricted these filters can get with even normal vehicle operation:

dirty and clean engine air filters
Dirty and Clean Engine Air Filters
dirty and clean engine air filters 2
Dirty and Clean Engine Air Filters 2

How about the cabin air filter, what is the deal with that?

Well, your cabin air filter does just what it sounds like: it resides in the ventilation system and it filters outside air entering the cabin. Does it get dirty? Take a look at these pictures and see for yourself:

dirty cabin air filter
Dirty Cabin Air Filter
Dirty cabin air filter 2
Dirty Cabin Air Filter 2

Your cabin air filter traps dust, pollen, hair, particulates, pollution, exhaust fumes, animal waste (yes, animals like to reside under your hood sometimes), basically all manner of substances that you do not want going into your nose, mouth and lungs. Think of your cabin air filter as an investment in your respiratory health, because that’s exactly what it is! Here is a fresh cabin air filter, wouldn’t you rather be breathing air that passes through this?

Clean cabin air filter
Clean Cabin Air Filter

Here is a smart-consumer suggestion: When you take your vehicle in for service, and the shop or dealership recommends new air filters, ask them to send you pictures of the air filters in your vehicle, so you can see for yourself before authorizing replacement. You can also ask them to keep the old filter for your inspection. At Midwest Performance Cars, we take pictures of all relevant vehicle conditions like these and send them to our customers along with our service recommendations. We do this because we want our clients to feel completely assured that what we are recommending is what truly needs attention, repair, or replacement.

We hope this article has “cleared the air” for you regarding the air filters on your vehicle and the need for good maintenance.
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