Air Filters. How complicated can they be? Honestly, not too complicated, but you need to know what to look for in an air filter and know when it should be replaced. There are certain quick lube places and other shops that try to sell you an air filter nearly every time you go there (usually at an incredible markup!).

In order for a car engine to run, it has to have fuel of course, but it also has to have air. Lots of air. And it can’t be just any old air; it must be filtered before the engine can ingest it. If the air wasn’t filtered before it entered the engine, your poor car engine would be sucking in all kinds of dirt, sand, bugs, etc. Not that I wouldn’t like to know how an unsuspecting insect would react in the combustion chamber of a car, but he needs to stay outside and not in my engine.

Enter the air filter.

Air filter inspection is usually done during periodic maintenance like an oil change, but a dirty air filter can cause problems in a vehicle if it is allowed to become clogged over years of service with no maintenance.

To remove the air filter for inspection or replacement, you are advised to consult your owner’s manual, but it’s usually just a few clips or screws to get the air box open.

The top filter is a new one, the bottom an old one. Which one does yours look like? 

Look at all the junk that can accumulate in your air filter over the course of a few months!

The proper way to inspect an air filter is to use a bright light source (shop light, flashlight, ceiling light, or even the sun) behind the clean (engine) side of the filter to check for debris lodged between the fins. You can also fold the filter’s fins back, but you run the risk of damaging the filter.
Air filters should be replaced when they’re dirty as in the above photos, every 12 months or 12,000 miles, or as recommended by the manufacturer.

Are all air filters the same? No, all air filters are not created equal. There could be many air filters for your car ranging from $6 or so to over $100, so which one is right for you? Most car air filters are the paper type or a cotton/synthetic media and are the less expensive ones. The more expensive filters tend to be oil-impregnated to trap more contaminants. Some are even lifetime filters that only need periodic cleaning instead of replacement (like the K&N, for example).

Which one should you get? The ordinary paper or cotton media filter is fine and is what most manufacturers use from the factory. Personally, I prefer to spend a few bucks more on a premium filter like a Purolator PureOne filter. These are just a little bit more expensive than the cheapies, but not quite as pricey as the high performance ones. They are oil-impregnated to trap more dirt, but they don’t require any maintenance and are cheap enough to replace at the specified intervals.

Now go inspect your air filter!