Cadillac 2006 STS - Manual (Page 334)

For V8 Engine Vehicles Only 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.
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