Video tutorial on how to replace the air filter on your vehicle. Having a dirty or plugged air filter can cause a variety of issues such as poor fuel mileage, decreased performance, and idling issues. Maintenance intervals depend on what vehicle manufacturers suggest, but as a generic specification it's good to change your air filter at about 30,000km or about 20,000 miles. This will also be dependant on your driving conditions, if you're located in an area with more or less dust or airborne contaminants. This particular tutorial was done on a 1998 Ford Ranger 2.5L 4 cylinder. The other vehicle I demonstrated in the video was a 1997 BMW 540i E39 4.4L V8 M62.