1998 GMC Suburban Owner's Manual - Page 309

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 If any one of these is true for YOLI,use the short tripkity maintenance schedule: 0 If none of them is true, ~1se long trip/highway the maintenance schedule. Change the oil and filter every 7,500 miles ( I 2 500 km) or 12 months -- whichever occurs first. Driving a vehicle with a fully warmed engine under highway conditions causes engineoil to break down slower. What to Do with Used Oil Did you know that used engine oil contains certain elements that may be unhealthy for your skin and could even cause cancer? Don't let used oil stay on your skin for very long. Clean your skin and nails with soap and water, or a good hand cleaner. Wdsh or properly throw away clothing or rags containing used engine oil. (See the manufacturer's warnings about the use and disposal of oil products.) Used oil can be a real threat to the environment. If you change your own oil, be sure to drain a l l free-flowing oil from the filter before disposal. Don't ever dispose of oil by putting it in the trash, pouring it on the ground, into sewers, 01- into streams or bodies of water. Instead, recycle it by taking it to a place that collects used oil. If you have a problem properly disposing of your used oil, ask your dealer, a service station or a local recycling center for help. 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). You operate your vehicle in dusty areas or off-road frequently. You frequently tow a trailer or use a carrier ontop of your vehicle. The vehicle is used for delivery service, police, taxi or other commercial application. 0 0 0 0 Driving under these conditions causes engineoil to break down sooner. If any one of these is true for your vehicle, then you need to change youroil and filter every 3,000 miles ( 5 000 km) or 3 months -- whichever occurs first.