2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 484

5. Inspect or replace the engine air cleaner/filter. 6. Reinstall the cover and tighten the screws. Automatic Transmission Fluid (4-Speed Transmission) When to Check and Change Automatic Transmission Fluid A good time to check the automatic transmission fluid level is when the engine oil is changed. Change the fluid and filter at the intervals listed in Scheduled Maintenance on page 7‑3 and be sure to use the transmission fluid listed in Recommended Fluids and Lubricants on page 7‑13. { WARNING: 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 flames if the engine backfires. Use caution when working on the engine and do not drive with the air cleaner/filter off. 6-24