1996 GMC Safari Owner's Manual - Page 244

As shown in the chart, SAE 5w-30 is best for your vehicle. However, you can use SAE IOW-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. When to Change Engine Oil See if any one of these is true for you: Most trips are less than 5 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 trailer orguse a carrier on top of your vehicle. The vehicle is used for delivery service, police, taxi or othercommercial application. Driving under these conditions causes engine to oil break down sooner. If any one of these is true for your vehicle, then you need to change your oil and filter every 3,000 miles ( 5 000 km) or 3 months -- whichever occurs first. If none of them is true, change the oil and filter every 7,500 miles ( 12 500 km) or 12 months -- whichever occurs first. Driving a vehicle with a fully warmed engine under highway conditions causes engine oil to break down slower. INOTICE: Use only engineoil with the American Petroleum Institute CertifiedFor Gasoline Engines "Starburst" symbol. Failure to use the recommended oil can resultin engine damage not covered by your warranty. GM Goodwrench@oil meets all the requirements for your vehicle. Engine Oil Additives Don't add anything to your oil. Your GM dealer is ready to advise if you think something should be added. 6-14