1996 GMC Sonoma Owner's Manual - Page 337

Long Tripmighway Maintenance Schedule 100,000 Miles (144 000 km) c Rotate tires. See "Tire Inspection and ] Rotation" in the Index for proper rotation pattern and additional information. 0Drain, flush and refill cooling system (or every 60 months since last service, whichever occurs first). See "Engine Coolant" in the Index for what to use. Inspect hoses. Clean radiator, condenser, pressure cap and neck. Pressure test the cooling system and pressure cap. An Emission Control Service.? 0Inspect spark plug wires. An Emission Control Service. 0Replace spark plugs. An Emission Control Service. (Continued) DATE ACTUAL MILEAGE SERVICED BY 7-45