1998 GMC Suburban Owner's Manual - Page 308

RECOMMENDED SAE VISCOSITY GRADE ENGINE OILS FOR BEST FUEL ECONOMY AND COLD STARTINC, S E L E 6 THE LOWEST cn,E VISCOSITY GRADE OIL FORTHE EXPECTED TEMPERATURE RANGE. ~~~ As shown in the chart, SAE 5W-30 is best for your vehicle. However, you can use SAE 1OW-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. HOT WEATHER LOOK FOR MIS SYMBOL 1 a 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 Goodwrench@oil meets all the requirements for your vehicle. If you are in an area where the temperature falls below -20°F (-29"C), consider using either a11SAE 5W-30 synthetic oil or an SAE OW-30 oil. Both will provide easier cold starting and better protection for your engine at extremely low temperatures. . SAE 1OW-30 I 1-30 RED COLD WEATHER DO NOT USE SAE 2OW-50 OR ANY OTHER GRADE OIL NOT RECOMMENDED 6-16