1. Increased fuel efficiency:
One of the biggest reasons to change your air filter regularly. Some studies indicate that replacing a dirty air filter increases fuel mileage on older, carburated cars by as much as 14 percent if the filter is so dirty it affects driveability. In addition, changing a clogged air filter can potentially increase acceleration by 6 to 11 percent on modern fuel-injected cars. Other studies claim a 10 percent increase in gas mileage and up to 15¢ per gallon fuel savings. Regardless of the exact figures, it is obvious that a clean air filter improves air flow to the engine and increases engine performance and gas mileage.
2. Reduced emissions:
Clogged air filters can reduce air flow to the engine, literally choking it, and as a result affect the emission control systems of the car causing an incorrect air-fuel mixture and spark plug ignition problems which can lead to serious driveability issues. Spark plugs can become fouled which often times result in an engine miss or rough idle, while also greatly affecting fuel mileage. It can also increase engine deposits caused by having too rich of a fuel mixture and may cause the "Service Engine Soon" light to illuminate. Increased air flow to the engine allows it operate properly reducing fuel consumption and reducing emissions.
3. Prolongs engine life:
Changing the air filter regularly helps prolong engine life because the air filter is designed to trap damaging dirt and debris that can damage internal engine parts such as the cylinders and pistons. Engine damage can occur from particles as small as a grain of salt and result in costly repairs.
4. Inexpensive and quick fix:
An air filter is one of the least expensive maintenance components to replace and can be done by doing it yourself. It is important to make certain the replacement air filter is designed for your exact make and model of car. On newer, fuel-injected cars, the air filter is usually located near the top front or side of the engine by the throttle body. The air filter is rectangular in shape and enclosed in a rectangular, black plastic housing that will normally have clips or screws keeping it closed. On older, carburated cars, the air filter is round and located in a round metal housing above the carburator that is secured by a wing nut.