1998 Oldsmobile 88 Owner's Manual - Page 243

As shown in the chart, A E 1OW-30 is best for your S vehicle. However, youcan use SAE 5W-30 if it's going to be colder than F (16"C) before your next oil 60" SA change. When it's very cold, you should use E 5W-30. These numbers on oil container show its an viscosity, or thickness. Do not use other viscosity oils, such asS A E 20W-50. Engine Oil Additives Don't add anything to your Your retailer is ready to oil. advise if you think something should be added. When to Change Engine Oil If any one of these is true for you, use the short trip/city maintenance schedule: 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@ meets all the requirements oil for your vehicle. If you are in an area where the temperature falls below -20°F (-29"C), consider using either an SAE 5W-30 syntheticoil or an SAE OW-30 oil. Both will provide easier cold starting and better protection for your engine at extremely low temperatures. Most trips are less than5 to 10 miles (8 to 16 km). This is particularly important when outside temperatures are below freezing. Most trips include extensive idling (such as frequent driving in stop-and-go traffic). Most trips are through dusty areas. You frequently tow a traileror use a carrier on top of your vehicle. The vehicle is used for delivery service, police, taxi or other commercial application. Driving under these conditions causes engine to oil break down sooner. If any of these is true for your one vehicle, then you need to change your oil and filter m or every 3,000 miles(5 000 k ) 3 months-- whichever occurs first. 6-14 !