1996 GMC Safari Owner's Manual - Page 340

I Long Tripmighway Maintenance Schedule 100,000 Miles (166 000 km) 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. 0Replace spark plugs. An Emission Control Service. IJ Inspect Positive CrankcaseVentilation (PCV) valve. An Emissiotl. Control Service. 0Inspect spark plug wires. An Emission Control Service. 7-40