2006 Cadillac STS-V Owner's Manual - Page 365

If the level is below the bottom of the filler plug hole, located on the rear axle, you'll need to add some lubricant. Add enough lubricant to raise the level to the bottom of the filler plug hole. How to Check Lubricant What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See Recommended Fluids and Lubricants on page 6-12. Front Axle When to Check and Change Lubricant It is not necessary to regularly check the front 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. A. Drain Plug B. Filler Plug To get an accurate reading, the vehicle should be on a level surface. If the level is below the bottom of the filler plug hole, located on the front axle, you may need to add some lubricant. What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See Recommended Fluids and Lubricants on page 6-12. 5-53