1997 GMC Savana Van Owner's Manual - Page 310

Maintenance Schedule Short TripKity Intervals -- Gasoline Engines Every 100,000 Miles (166 000 km): Spark Plug Wire Inspection. Spark Plug Replacement. Positive Crankcase Ventilation (PCV) Valve Inspection. Every 150,000 Miles (240000 km): Cooling System Service (or every 60 months, whichever occurs first). These intervals only summarize maintenance services. Be sure to follow the complete maintenance schedule on the following pages. Follow this maintenanceschedule onZy if none of the conditions from the Short TripKity Maintenance Schedule is true. Do not use this schedule if the vehicle is used for trailer towing, driven in a dusty area or used off paved roads. Use the Short Trip/City schedule for these conditions. Driving ci vehicle with n fL1lly warmed engine under highway conditions causes engine oil to break down slower.