2002 GMC Sonoma Owner's Manual - Page 326

As in the chart shown previously, 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. 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. When to Change Engine Oil NOTICE: Use only engine oil with the American Petroleum Institute Certified For Gasoline Engines starburst symbol. Failure to use the recommended oil can result in engine damage not covered by your warranty. GM GoodwrenchR oil meets all the requirements for your vehicle. If any one of these is true for you, use the short trip/city maintenance schedule: D Most trips are less than 5 miles (8 km). This is particularly important when outside temperatures are below freezing. -20_F (-29_C), consider using either an SAE 5W-30 synthetic oil or an SAE 0W-30 oil. Both will provide If you are in an area where the temperature falls below D Most trips include extensive idling (such as frequent driving in stop-and-go traffic). D Your vehicle has a 2200 L4 (Code 5) flexible fuel engine and you have used E-85 ethanol fuel. D You frequently tow a trailer. D The vehicle is used for delivery service, police, taxi or other commercial application. easier cold starting and better protection for your engine at extremely low temperatures. 6-16