2005 GMC Sierra 1500 Pickup Owner's Manual - Page 421

{CAUTION: Operating the engine with the air cleaner/filter off can cause you or others to be burned. The air cleaner not only cleans the air; it helps to stop flame if the engine backfires. If it is not there and the engine backfires, you could be burned. Do not drive with it off, and be careful working on the engine with the air cleaner/filter off. Automatic Transmission Fluid (Except Allison Transmission®) When to Check and Change A good time to check your automatic transmission fluid level is when the engine oil is changed. Change both the fluid and filter every 50,000 miles (83 000 km) if the vehicle's GVWR is over 8,600 or if the vehicle is mainly driven under one or more of these conditions: • In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher. • In hilly or mountainous terrain. • When doing frequent trailer towing. • Uses such as found in taxi, police or delivery service. If your vehicle's GVWR is not over 8,600 and you do not use your vehicle under any of these conditions, change the fluid and filter every 100,000 miles (166 000 km). See Scheduled Maintenance on page 6-4. 5-27