2014 Chevrolet Silverado 3500 HD Crew Cab Owner Manual - Page 396

10-30 Vehicle Care Also, if a vehicle has just been driven before checking the fluid level, it may appear lower than normal because fluid has traveled out along the axle tubes and has not drained back to the sump area. Therefore, a reading taken five minutes after the vehicle has been driven will appear to have a lower fluid level than a vehicle that has been stationary for an hour or two. Remember that the rear axle assembly must be supported to get a true reading. What to Use Refer to Recommended Fluids and Lubricants on page 11-12 to determine what kind of lubricant to use. How to Check Lubricant Rear Axle When to Check Lubricant It is not necessary to regularly check rear 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. All axle assemblies are filled by volume of fluid during production. They are not filled to reach a certain level. When checking the fluid level on any axle, variations in the readings can be caused by factory fill differences between the minimum and the maximum fluid volume. 2500HD with 6.0 L All Other Series and Engines