1994 GMC Suburban Owner's Manual - Page 353

7. TRANSMISSIONSERVICE? Automatic Transmission- Change the transmission fluid and filter every 15,000 miles (25 000 km) for vehicles under 8,600 GVWR or every 12,000 miles (20 000 km) for vehicles over 8,600 GVWR if the vehicle is mainly driven under one or more of these conditions: 0 0 In heavy city traffic. Where the outside temperatureregularly reaches YO" F (32 O C) or higher. In hilly or mountainous terrain. Frequent trailer pulling. Uses such as taxi, police, delivery or other commercial service. 0 0 If the vehicle is not used mainly under any of these conditions,change the fluid and filter every 30,000 miles (50 000 km) for vehicles under 8,600 GVWR or every 24,000 miles (40 000 km) for vehicles over 8,600 GVWR see "Automatic Transmission Fluid" in the Index for more information. Manual Transmission-Transmission fluid does not require periodic changing. 8. CDRV SYSTEM INSPECTION* - Check the Crankcase Depression Regulator Valve System for any worn, plugged or collapsed hoses. Have the system checked as described in the Service Manual. 9. FUEL FILTER REPLACEMENT*$- Replace the fuel filter at the specified interval or sooner if clogged. 10. SPARK PLUG REPLACEMENT* Replace spark plugs with the type listed in Section 6. See "Specification Charts" in the Index. ~ 11. SPARK PLUG WIRE INSPECTION- Clean wires and inspect for burns, cracks or other damage. Check the wire boot fit at the distributor and at the spark plugs. Replace wires as needed. * An Emission Control Service $The California Air Resources Board has determined that the failure to perform this maintenance item will not nullify the emission warranty or limit recall liability prior to the completion of the vehicle useful life. General Motors, however, urges that all recommended maintenance services beperformed at the indicated intervals and the maintenance be recorded. ?A fluid loss in these systems may indicate a problem.Have them inspected and repaired at once. 7-19