* Oil type: This will likely be a synthetic blend or full synthetic oil, and will specify the viscosity grade (e.g., 5W-30, 0W-20). Do not assume; check your manual.
* Oil specifications: This might include API certifications (like SN Plus or SP) and GM's own dexos specifications (dexos1 or dexos2). Meeting these specifications is crucial for engine protection.
Using the incorrect oil can severely damage your engine. Looking up the information online without knowing the exact year and engine could lead to using the wrong oil. Your owner's manual is the definitive source.