1999 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 313

yellowblue As shown in the 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. Engine Oil Additives Don't add anything to your oil. Your dealer is ready to advise if you think something should be added. _ _ When to Change Engine Oil Your vehicle has a computer that lets you know when to change your engine oil. This is not based on mileage, but on engine revolutions and engine operating temperature. When the computer has calculated that the oil needs changing, the Oil Life Monitor will indicate that a change is necessary. The mileage between oil changes will vary depending on how you drive your vehicle -- usually between 3,000 miles (5 000 km) and 7,500 miles (12 500 km) since your last oil change. Under severe conditions, the indicator may come on before 3,000 miles (5 000 km). Never drive your vehicle more than 7,500 miles (12 500 km) or 12 months (whichever occurs first) without an oil change. The system won't detect dust in the oil. So, if you drive in a dusty area, be sure to change your oil every 3,000 miles (5 000 km) or sooner. Remember to reset the CHANGE ENGINE OIL message whenever the oil is changed. 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. -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 easier cold starting and better protection for your engine at extremely low temperatures. 6-15