Are Car Air Filters Universal? (Beginners Guide)


When I was an apprentice mechanic, running to parts store and getting back to the shop with the “right parts” was like winning the lottery. Thankfully, it almost foolproof today.

Car air filters are not universal, they are model specific. However, some makers may share power plants and therefore service parts will be identical.

In this post, I’ll share the right way to order the your filter. How to fit your air filter and why a good filter is so important to your car’s health.

Air filters come in many different shape, size and porosity. The right filter for your car is extremely important, an ill fitting filter will allow unfiltered air enter the engine which could badly damage your engine.

It’s not uncommon for different car manufacturers to collaborate on engine development. The same engine is often found in different makes and many models across the range. Service parts for these cars are usually interchangeable.

Air filter

What Is An Air Filter And Why Is It Important?

Car engines use fuel and air proportionally, the more fuel you burn the more air your engine sucks in. But before the air gets to mix with the fuel, it first passes through an air filter.

Most cars use paper filters, the material is arranged in a pleated formation which increases airflow by increasing the surface area.

Although we call them paper filters, it’s not paper as we know it, it’s a resin treated paper mixed with synthetic fibres.

Air filtering removes 90% plus airborne contaminates.

Every car has an air filter which has two main functions:

  • Filter the air
  • Settle the air

Filtered Air

Air is extremely important to all vehicles, and that’s because the air around us contains Silica dust and other debris.

Silica dust is basically rock partials, which, if not for your air filter, would sand blast your engine intake system and cause premature internal engine wear.

You’ll find Silica dust in soil, roads, concrete, and the levels of silica increase anywhere these materials are worked. Manufacturing, fabrication, construction etc.

A car air filter looks unimpressive and unassuming. But it’s responsible for keeping abrasive dust as small as 5 microns from destroying your motor. As a reference, a human hair is about 50 microns, so when you think about it, your air filter is pretty advanced kit.

Maf Sensor cleaning

Settling Airflow:

If not for the air filter, your car engine would gulp air like a hairy lab on a long run. Air entering your car engine needs to be uniform and settled. The large pleated air filter helps even out the distribution of air entering the intake system.

A sensor known as MAF (Mass Air Flow) positioned inside the intake air ducting measures air flow volume before it enters the engine. This info is relayed to the ECM (Engine Control Module) aka PCM.

Airflow volume is mission critical information and accuracy is key.

More evenly distributed air makes for better airflow readings resulting in a more predictable, responsive engine.

Modern cars as you know are ran by computers that are precisely designed and programmed around tested tolerances.

While it’s possible to run your car without an air filter, you may even notice a small increase in power. However in the longer term, dirt on the MAF may cause failure and symptoms such as:

VIN plate

How To Order A Car Air Filter

It’s Saturday morning you’ve got a window of one hour to get the job done. You’ve got your air filter, tools and you’ve done your homework.

Pulling the filter was easier than you thought, but wait….that filter doesn’t look right…..Arghhh!!!!

I was that soldier and it drives me crazy, it doesn’t happen to often any more because we now order parts by VIN (Vehicle Identification Number).

All good auto part stores are computerised, the shop assistant enters your VIN, your car is identified and you confirm your make and model, that’s it!

You’ll find your VIN in various locations on your car, you can google your model but the more common places they like to hide them include:

  • Inside the door shut
  • Under the hood, either side to the engine bay
  • Under the hood on the shut panel
  • On the windshield base
  • In the trunk

I just take a pic of the VIN plate with my phone and bring it to the parts shop.

Can You Clean The Air Filter?

Yes, you can clean the filter, but it’s not a substitute for replacing it. Knocking the pare filter elements against a hard surface will remove large loose debris, if you have compressed air that will help remove finer particles.

Use a dust mask if you’re attempting this, don’t wan’t this crap in your lungs.

Don’t be tempted to wash or oil these filters, that will render them useless and likely your vehicle won’t run or will run poorly.

How Often Should You Change The Air Filter?

Under normal conditions, the air filter should be changed every 15,000 miles. But if you live in a dusty environment you’ll need to inspect it more often, about every five thousand.

In dusty conditions, expect to replace the filter every 10,000 miles.

If your engine is turbo charged, you’ll need to take special care with air filters, any dirt sucked into the compressor wheel can be catastrophic.

How Do I Check My Car Air Filter?

Checking your cars air filter is easy, most cars air box will be easy to identify and access. Some manufacturers will even fit a tool-less air box which makes checking and replacing the filter super easy.

The air box contains the air filter, it’s likely fitted to one or other side of the engine bay. It’s likely a black plastic rectangle shaped box with large pipework attached. The air filter box opens in half to reveal the air filter.

Most filters are pleated paper, they must not be oiled or washed.

Replacing is really simple, follow these steps.

Step One:

Identify the air filter housing.

Step Two:

MAF sensor

Remove the air box lid fasteners, the downstream duct-work can usually remain in place. In some cases you may need to unplug the MAF sensor connector.

Step Three:

Remove the air filter and clean the air box base.

Step Four:

Inspect the air filter by holding it to strong light, if you can’t see light through the pleated paper illuminate, it’s time to change it out.

Step Five:

If your filter passes the light test. Go ahead and tap it on the ground to remove grit. It you have compressed air, blow the filter from upstream to down stream.

Foam and performance filters such as K&N may be washed and oiled, but check with the filter maker first, generally a special sticky air filter oil is recommended.

Step Six:

Fit the filter in reverse order, remembering to refit any ducting or sensor connectors.

Caution: Be sure not to leave any tools or fasteners inside the air box, they could get sucked into the engine when started, causing engine failure.

Turbo charger

Does Changing The Air Filter Improve Performance?

A blocked air filter will cause the engine to choke, the car will feel sluggish and may idle erratically and possibly set some fault codes in the ECM.

An unrestricted air system is important for all engines and especially for turbo charged power plants.

Turbo charged engines are becoming more common as manufacturers are under increasing pressure to achieve more power from smaller more efficient engines.

Turbos as you may know work by using spent exhaust gasses to power a compressor wheel which pushes a larger volume of air into the engine, thereby producing more power.

Turbo wheel

However compressor vanes turn at over 200’000 rpm and while strong, any abrasive grit that makes it past the air filter can destroy it.

A new turbo charger can run into 1000s of dollars, an air filter is twenty dollars.

What about upgrading to a performance filter like a K&N? Sure a performance air filter can improve power, however it is worth noting proper air filtering is important and making modifications to your car could void your manufacturers warranty.

Many performance filters are oiled which helps catch debris while increasing airflow. Some air filter oil will be ingested by the engine and can contaminate the MAF sensor.

You already know that the MAF is critical to your engine performance, any contamination can lead to poor running, fuel efficiency, higher emissions and sensor failure.

All that said, many cars run just fine with performance filters fitted, just be sure to follow the manufacturers maintenance schedule.

Related Questions

How much does an air filter cost? A car engine air filter usually costs about twenty dollars, but a performance car air filter may cost more about $80.

John Cunningham

John Cunningham is an Automotive Technician and writer on Rustyautos.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write articles that help fellow gear-heads with all aspects of classic car ownership, from tires to roof aerials and everything in between.

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