2007 GMC Sierra 1500 Pickup Owner's Manual - Page 527

Rear Axle When to Check Lubricant It is not necessary to regularly check rear axle fluid unless you suspect there is a leak or you hear an unusual noise. 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. 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. How to Check Lubricant 1500 Series Shown, 2500 Series Similar To get an accurate reading, the vehicle should be on a level surface. • The proper level for the 1500 Series is from 5/8 inch to 1 5/8 inch (15 mm to 40 mm) below the bottom of the filler plug hole. • The proper level for the 1500HD Series, 2500 Series and 2500HD Series with the 6.0L V8 engine (RPO LQ4) is from 0 to 1/2 inch (0 to 13 mm) below the bottom of the filler plug hole. 527