1998 GMC Suburban Owner's Manual - Page 390

I Short TriplCity Maintenance Schedule -- Gasoline Engines I DATE 100,000 Miles (I66 000 km) 0 Inspect spark plug wires. An Evlzissiol? Control Service. 0 Replace spark plugs. An Emission Control Senrice. Change automatic transmission fluid and filter if the vehicle is mainly driven under one or more of these conditions: - In heavy city traffic where the outside temperature regularly reaches 90°F (32 C) or higher. - In hilly or mountainous terrain. - When doing frequent trailer towing. - Uses such as found in taxi, police or delivery service. 0 If you haven't used your vehicle under severe service conditions listed previously and, therefore, haven't changed your automatic transmission fluid, change both the fluid and filter. 0 Inspect Positive Crankcase Ventilation (PCV) valve. An Emission Control Service. O SERVICED BY: 150,000 Miles (240 000 km) 0 Drain, flush and refill cooling system (or every 60 months since last service, whichever occurs first). See"EngineCoolant" in theIndex for what to use. Inspect hoses. Clean radiator, condenser, pressure cap and neck. Pressure test cooling system and pressure cap. An Emuhion Control Service. DATE SERVICED BY: MILEAGE 7-26