2011 Chevrolet Silverado 1500 Regular Cab Owner's Manual - Page 441

Vehicle Care When to Change Lubricant Refer to Scheduled Maintenance on page 11‑2 to determine how often to change the lubricant. What to Use Refer to Recommended Fluids and Lubricants on page 11‑8 to determine what kind of lubricant to use. 10-35 Front Axle When to Check and Change Lubricant It is not necessary to regularly check front axle fluid unless a leak is suspected, or an unusual noise is heard. A fluid loss could indicate a problem. Have it inspected and repaired. How to Check Lubricant To get an accurate reading, the vehicle should be on a level surface. 1500 Series A. Fill Plug B. Drain Plug All Except 1500 Series A. Fill Plug B. Drain Plug . When the differential is cold, add enough lubricant to raise the level from 0 mm (0 in) to 3.2 mm (1/8 in) below the fill plug hole. When the differential is at operating temperature (warm), add enough lubricant to raise the level to the bottom of the fill plug hole. .