2003 Chevrolet Corvette Owner's Manual - Page 331

50,000 Miles (83000 km) Change automatic transmission fluid and filter if the vehicle is mainly driven under one or more of these conditions: - In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher. - In hilly or mountainous terrain. - Uses such as high performance operation. 100,000 Miles (166 000 km) * Replace spark plugs. An Emission Control Service. Inspect spark plug wires. An Emission Control Service. * Change automatic transmission fluid and filter if the vehicle is mainly driven under one or more of these conditions: - If you do not use your vehicle under any of these conditions, change the fluid and filter at 100,000 miles (166 000 km). Manual transmission fluid doesn't require change. In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher. In hilly or mountainous terrain. Uses such as high performance operation. - 60,000 Miles (100 000 km) Replace engine air cleaner filter. An Emission Control Service. 75,000 Miles (125 000 km) Inspect engine air cleaner filter if you are driving in dusty conditions. Replace filter if necessary. An Emission Control Service. (See footnote f.) If you haven't used your vehicle under severe conditions listed previously and, therefore, haven't changed your automatic transmission fluid, change both the fluid and filter. Manual transmission fluid doesn't required change. 150,000 Miles (240 000 km) Drain, flush and refill the cooling system (or every 60 months since last service, whichever occurs first). See Engine Coolant on page5-23 for what to use. An Emission Control Service. 90,000 Miles (150 000 km) * Replace engine air cleaner filter. An Emission Control Service. 6-6 * Inspect engine accessory drive belt. An Emission Control Service.