Learn when it is time for Air Filter Maintenance. Jeff Payne, Preventive Maintenance Instructor with Caterpillar, explains best way to keep your Primary and Secondary air filters in tip top shape. For more maintenance tips please visit http://www.cat.com/en_US/support/maintenance.html. Air Filters are available to purchase online at: https://parts.cat.com//en/catcorp/search/air-filters