How often should an engine air filter be changed?
The air filter is the part that filters the air entering your engine, protecting it from sand and dust. As you drive, the air filters becomes contaminated. At some point, it will need to be replaced, but when? Can a dirty air filter affect your gas mileage? Is there a way to check its condition?
An air filter is installed inside the air filter box. It's made of pleated paper-like material. The air flows from the bottom up, so dirt and larger objects are trapped in the box under the filter.
As the air filter clogs up, the air flow into the engine becomes more and more restricted. It adds strain on your engine, making it harder to "breathe." Due to increased vacuum, some particles could be sucked through the filter and scratch the engine pistons and cylinder walls. For the same reason, the engine may start consuming more oil.
Symptoms of a dirty air filter include lack of power on hard acceleration and at higher RPMs, although it's not always noticeable.
The fuel economy may also be affected, although not by much. In extreme cases, the "Check Engine" warning light may illuminate on the dash.
How often should an air filter be replaced? Can its condition be checked? For most cars, air filter replacement intervals vary between 15,000 and 30,000 miles, depending on the driving conditions. If you regularly drive on unpaved roads, it should be changed more often. If you don't drive a lot, the filter should be replaced at least every 3 years, as with age it becomes brittle. An old filter can tear, allowing dirt to enter the engine.
An air filter is usually checked during your regular oil changes. Your mechanic can check its condition and let you know if it needs to be replaced.
For example, compare these two air filters in the photo. The filter on the right has been changed one year ago, but the owner of this Honda drives over 24,000 miles a year. Now it looks dirty, so the owner decided to replace it again.
If you want to check it yourself, your vehicle's owner's manual has the engine compartment map. In some cars, to open an air filter box you will need some tools, like an 8mm or 10mm socket or a screwdriver. In other cars, the air filter box cover is held by a few clips. Replacing the air filter in the repair shop is not very expensive: $10-$30 labor plus $19-$45 part.
Is it important to have an air filter replaced at a dealer or can a fast lube shop do the job? Replacing an air filter is fairly easy in most cars and can be done in any garage, however using a factory (OEM) part from a dealer will ensure that it fits properly. If you decide to opt for an aftermarket part, invest a little extra for a premium brand for better engine protection.
Is it necessary to replace a cabin (pollen) filter whenever an engine air filter is replaced? It's not necessary, however if the engine air filter is dirty, the cabin filter is likely to be in the same condition.