When to replace air filter

How to tell if your car air filter needs changing is important because a clean air filter is a necessity for the proper operation of a car. A clean air filter results in improved gas mileage, better acceleration, increased engine life, lower emissions and overall improved engine performance. Not only does an air filter clean the air entering the engine but it also prevents debris from entering the engine and causing damage. For each gallon of fuel the engine burns, it requires up to 10,000 gallons of clean air; thus why the air filter is such an important engine component.

As an air filter becomes dirty, the capacity for it to filter the air going into the engine is reduced. Because of this, the engine is not able to function properly, which may cause numerous drivability issues. Examining and replacing the air filter, as indicated by the manufacturer’s maintenance schedule, is important but often times overlooked.

Symptoms of a dirty air filter vary but will often times include a noticeable decrease in gas mileage. Other symptoms are potential ignition problems cause by fouled spark plugs. A dirty air filter prevents the necessary volume of clean air from reaching the engine which affects the emission control systems of the car; reducing air flow and causing a too rich air-fuel mixture which can foul the spark plugs. Fouled spark plugs can create an engine miss, rough idle and even starting problems. In addition, a too rich fuel mixture increases engine deposits which may even cause the "Service Engine Soon" light to come on.

A brand new air filter will generally appear white to off white. A visual inspection of an air filter may reveal that the air filter has become darkened or full of debris. A visual inspection can be done by examining the air filter in bright light. However, an air filter can become clogged with dust and even pollen that may not be easily seen. Therefore, most car manufacturers recommend replacement every 12,000 to 15,000 miles regardless of whether or not the air filter appears to be clean. Cars driven in dusty or frequent stop and go conditions will requires a more frequent check and replacement of the air filter.

Changing an air filter is relatively easy and inexpensive. The air filter is located near the top driver’s side of the engine in a rectangular shaped plastic housing that either snaps or screws shut on most new cars. Older cars with carburetors usually have a circular shaped air filter located in a metal housing on top of the engine that fastens with a wing nut. Make certain to use the correct air filter replacement for your make and model of car.

In some situations, a clean air filter will improve gas mileage as much as 14% and may increase acceleration up to 11% depending on the make and model of car. This translates to a potential per gallon fuel savings of up to 15 cents. Learning how to tell if your car air filter needs changing will help you keep your car running properly and ultimately save money on gas and repairs.