1995 Buick Century Owner's Manual - Page 214

RECOMMENDED SAE VISCOSITY GRADE ENGINE O S I L FOR BEST FUEL ECONOMY AND COLD STARTING, SELECTTHE LOWEST SAE VISCOSITY GRADE OIL FOR THE EXPECTED TEMPERATURE RANGE. ~ - As shown in the chart, SAE SW-30 is best for your vehicle. However, you can use SAE IOW-30 if it's going to be 0°F (-lS°C) or above. These numbers on an oil container show its viscosity, or thickness. Do not use other viscosity oils, such as SAE 2OW-SO. HOT WEATHER LOOK FOR MIS SYMBOL NOTICE: Use only engine oil with the American Petroleum Institute Certified For Gasoline Engines "Starburst" symbol. Failure to use the proper oil can result in engine damage not covered by your warranty. GM Goodwrench@oil (in Canada, GM Engine Oil) meets all the requirements for your vehicle. Engine Oil Additives SAE PREFERRED 5w-30 Don't add anything to your oil. Your Buick dealer is ready t o advise if you think something should be added. WEATHER DO NOT USE SAE 2OW-50 OR ANY OTHER GRADE OIL NOT RECOMMENDED 6-10