Cadillac 2007 CTS Owner's Manual page 348

What Kind of Engine Oil to Use
348
Look for two things:
•
GM4718M
Your vehicle's engine requires a special oil
meeting GM Standard GM4718M. Oils meeting
this standard may be identified as synthetic.
However, not all synthetic oils will meet this GM
standard. You should look for and use only an
oil that meets GM Standard GM4718M.
Notice: If you use oils that do not have the
GM4718M Standard designation, you can cause
engine damage not covered by your warranty.
•
SAE 5W-30
As shown in the viscosity chart, SAE 5W-30 is
best for your vehicle.
These numbers on an oil container show its
viscosity, or thickness. Do not use other
viscosity oils such as SAE 20W-50.