2004 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 414

Engine Air Cleaner/Filter See Engine Compartment Overview on page 5-12 for location of engine air cleaner/filter and change indicator (if equipped). How to Inspect Locate the filter change indicator. When the change indicator turns black or is in the red/orange "change" zone, replace the filter and reset the indicator. To inspect the air cleaner/filter, remove the filter from the vehicle and lightly shake filter to release loose dust and dirt. If the filter remains "caked" with dirt, a new filter is required. To inspect and replace the filter and reset the indicator (if equipped), do the following: When to Inspect If your vehicle is equipped with a filter change indicator it lets you know when the filter needs to be replaced. Vehicles with a restriction indicator, inspect the air cleaner/filter at every oil change and replace the filter when the indicator tells you to. Vehicles without a change indicator, inspect the air cleaner/filter at every oil change and replace it at the first oil change after 25,000 miles (40 000 km). The air cleaner/filter assembly is located on the front corner of the engine compartment on the passenger's side of the vehicle. 5-22