Tuesday, January 17, 2012

Does Changing Your Air Filter Really Help Fuel Economy

I change my air filter at the intervals specified in my owners' manual.

Whenever I'm getting my oil changed, the mechanic always tries to upsell me on an airfilter.  First of all, he charges $25 for an air filter I can buy at Sears or Autozone for $7.  I can get it for as low as $4.50 on Amazon.   It takes two minutes to change.

Secondly, he claims that changing your air filter helps your fuel economy.  I've been hearing this for years from people of all walks of life--mechanics, automotive insiders, clergymen--you name it.

A recent study at fueleconomy.gov suggests that for vehicles with engines built after ~1980, an unclogged air filter really does not help with fuel economy, but can help with acceleration time.  Tests suggest that replacing a clogged air filter on an older car with a carbureted engine may improve fuel economy 2 to 6 percent under normal replacement conditions or up to 14 percent if the filter is so clogged that it significantly affects drivability.

Typicacally, city drivers are supposed to replace their air filter every 15,000 miles (more frequently if you're frequently on dirt roads).  If you get your oil changed every 3000 miles, this means every fifth oil change--not every other oil change as the pushy mechanic suggests,

If you drive 1000 miles a month, that's once every 15 months, and again, replace it yourself according to the instuctions in the owners' manual.

If your mechanic is as pushy as mine, and you drive 1000 miles a month, you could save as much as $44 per year.


The Frugal Maestro


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