2010 Cadillac CTS Owner's Manual - Page 330

9-30 Vehicle Care How to Check Lubricant some lubricant. Add enough lubricant to raise the level to the bottom of the filler plug hole. Use care not to overtighten the plug. What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See Recommended Fluids and Lubricants on page 10‑7. All-Wheel Drive If your vehicle is equipped with all-wheel-drive, this is an additional system that needs lubrication. Transfer Case When to Check Lubricant It is not necessary to regularly check the transfer case 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. Rear Axle A. Drain Plug B. Fill 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 transfer case, you'll need to add 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.