Air filters on most engines are relatively easy to access, and you may check the location inside your owner’s manual when you need help. If you cannot tell by looking, yet it’s been more than 3 years or 30,000 miles, you most likely ought to get a new one. Nevertheless, you ought to be hesitant if every time you have an oil change the mechanic states you also need a new air filter. We’d expect most drivers can go more than a year, at least, and in all likelihood more than two years.

A blocked air filter won’t substantially have an effect on gas mileage, based on a 2009 study conducted for the U.S. Department of Energy, but it can hurt acceleration by 6% to 11%.

Acceleration is more difficult to measure than fuel economy, so you may not notice a gradual performance loss. For that reason, it’s a good idea to periodically visually check the engine air filter.