2001 Chevrolet Corvette Owner's Manual - Page 284

D SAE 5W-30 As shown in the viscosity chart, SAE 5W-30 is best for your vehicle. However, you can use SAE 10W-30 if it's going to be 0_F (-18_C) or above. These numbers on an oil container show its viscosity, or thickness. Do not use other viscosity oils such as SAE 20W-50. Oils meeting these requirements should also have the starburst symbol on the container. This symbol indicates that the oil has been certified by the American Petroleum Institute (API). You should look for this on the oil container, and use only those oils that are identified as meeting GM Standard 4718M and have the starburst symbol on the front of the oil container. Your vehicle's engine is filled at the factory with a Mobil 1R synthetic oil, which meets all requirements for your vehicle. Substitute Engine Oil: When adding oil to maintain engine oil level, oil meeting GM Standard GM4718M may not be available. You can add substitute oil designated SAE 5W-30 with the starburst symbol at all temperatures. If temperatures are above 0_F (-18_C), you may substitute SAE 10W-30 with the starburst symbol. Substitute oil not meeting GM Standard GM4718M should not be used for an oil change. Engine Oil Additives Don't add anything to your oil. The recommended oils with the starburst symbol are all you will need for good performance and engine protection. 6-15