CHEVROLET CORVETTE 2005 - Manual (Page 276)

What Kind of Engine Oil to Use
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.
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