2013 Chevrolet Impala Owner Manual - Page 302

11-8 Service and Maintenance (3) Or every four years, whichever comes first. (4) Or every five years, whichever comes first. See Cooling System on page 10‑11. (5) Or every 10 years, whichever comes first. (6) Inspect for fraying, excessive cracking, or damage; replace, if needed. . Footnotes - Maintenance Schedule Additional Required Services - Severe (1) Or every two years, whichever comes first. More frequent replacement may be needed if the vehicle is driven in areas with heavy traffic, areas with poor air quality, or areas with high dust levels. Replacement may also be needed if there is a reduction in air flow, excessive window fogging, or odors. (2) Check all fuel and vapor lines and hoses for proper hook-up, routing, and condition. Check that the purge valve, if the vehicle has one, works properly. Replace as needed. Special Application Services . Severe Commercial Use Vehicles Only: Lubricate chassis components every 5 000 km/ 3,000 mi. Have underbody flushing service performed once a year.