A dirty air filter can have a significant impact on the performance of your car. It reduces the amount of clean air that reaches the engine, which decreases its power and acceleration. Replacing the dirty engine air filter with a new, clean one can improve engine acceleration and fuel efficiency. Aftermarket air filters can lead to increases in engine performance and an increase in fuel mileage rating, although this may be more noticeable on older cars.
For newer models, some “performance” air filters can only make a negligible difference. A dirty air filter reduces the amount of air supplied to the engine, causing no fuel to burn. This fuel causes the formation of soot residues that accumulate at the tip of the spark plug. A decrease in fuel consumption is often a sign that something is wrong.
Air filter contributes to fuel efficiency, but a dirty filter can reduce oxygen flow. A vehicle must compensate for this by burning more fuel to compensate. As noted above, inadequate air in the engine can cause incomplete combustion of fuel in the combustion chamber. It's easy to forget about important technical aspects, such as engine filters, during normal day-to-day driving.
Something as simple as an air filter can cause everything from harmful emissions, fuel waste, damaged spark plugs and engine buildup. Replacing the air filter is actually one of the easiest DIY tasks you can perform on your vehicle, so 95% of the population should be able to change it themselves. An air filter won't be changed as often as oil, but it's a regular maintenance service that can be performed several times a year (approximately every 3,000 miles). Disposable paper filters have thousands of tiny pores, or air passages, that are excellent for trapping particles the same size or larger than their pores.
It's important to note that the inner layers of filter paper inside the air cleaner may have no visible debris or dust and dirt, even in bright light. Air filters are crucial to your car's performance, and if not maintained in proper repair, can cause setbacks to your car's longevity. Whether or not to clean an air filter depends on the type of air filter you use in your car. Paper filters are usually very economical, but quite efficient at trapping potential engine contaminants.
However, as with any “replacement estimate”, you can't really pinpoint a precise date on when to change the air filter.