1994 GMC Suburban Owner's Manual - Page 267

Engine Oil Additives Don't add anything toyour oil. Your GM dealeris ready to advise if you think something should be added. When to Change Engine Oil See if any one of these is true foryou: 0 0 Most trips are less than 4 miles (6 km). It's below freezing outside and most trips are less than 10 miles (16 km). The engine is at low speed most of the time (as in door-to-door delivery, or in stop-and-go traffic). 0 0 You tow a trailer often. Most trips are through dusty places. The vehicle is frequently operated off-road. 0 If any one of these is true for your vehicle, then you need to change your oil undfilter every 3,000 miles ( 5 000 k ) 3 months - whichever comes m or first. Light Duty Emissions: If none of them is true, change the oil every 7,500 miles ( 1 2 500 km) or 12 months - whichever comes first. Change the filter at the first oil change and at every other oil change after that. Heavy Duty Emissions: If none of them is true, change the oil every 6,000 miles (1 0 000 km) or 12 months - whichever comes first. Change the filter at the first oil change and at every other oil change after that if mileage determines when you change your oil. If time determines when you change your oil, change the filter each time you change your oil. Engine Coolant Heater (Engine Block Heater) An engine coolant heater can a big help if you have to park outside in be very cold weather, 0"F (-1 8°C) or colder. If your vehicle has this option, see "Engine Coolant Heater " in the Index. 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. Wash or properly throw away clothing or rags containing used engine oil. (Seethe manufacturer's warnings about the use and disposal of oil products.) 6-21