C4 --
Corvette Overview --

1991 Maint. Schedule
THE C4 CORVETTE - MAINTENANCE SCHEDULE
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Schedule 1
Follow Schedule 1 if your car is mainly operated under one or more of the following conditions:.
Schedule 2
Follow Schedule 2 only if none of the driving conditions specified in Schedule 1 apply.
The 1991 Corvette has an Engine Oil Life Monitor. This monitor will show drivers when to change their oil - usually between 3,000 miles (5,000 km) and 7,500 miles (12,500 km) since the last oil change.  Under severe conditions the indicator may come on before 3,000 miles (5,000 km).  Never drive your vehicle more than 7,500 miles (12,500 km) or 12 months whichever occurs first, without an oil change.

The system won’t detect dust in the oil.  If you drive in a dusty area be sure to change your oil every 3,000 miles (5,000 km) or sooner if the CHANGE OIL light comes on.  Remember to reset the Oil Life Monitor when the oil has been changed.  See “GM Oil Life System" (at the bottom of this page) for more information on resetting the system.

Explanation of Scheduled Maintenance Services:
1.) Engine Oil and Filter Change:  

2.) Chassis Lubrication:

3.) Engine Accessory Drive Belt Inspection:

4.) Cooling System Service:

5.) Transmission Service:

6.) Spark Plug Replacement:

7.) Spark Plug Wire Inspection:

8.) Air Cleaner Filter Replacement:

9.) Fuel Tank, Cap and Line Inspection:

Owner Inspection & Service Items
At Each Fuel Fill
NOTE:  It is important for you or a service station attendant to perform these underhood checks at each fuel fill.
Engine Oil Level Check:  
Engine Coolant Level Check:  
Windshield Washer Fluid Level Check:  

At Least Once a Month
Tire Inflation Check: 

At Least Once A Year
Key Lock Cylinder Service:  
Body Lubrication Service:  
Starter Switch Check:  
CAUTION: When you are doing this check, the vehicle could move suddenly.  If it does, you or others could be injured.  
Steering Column Lock Check:
Parking Brake and Automatic Transmission PARK (P) Mechanism Check:
CAUTION: When you are doing this check, your vehicle could begin to move. You or others could be injured and property could be damaged. Make sure there is room in front of your vehicle in case it begins to roll. Be ready to apply the regular brake at once should the vehicle begin to move.
Underbody Flushing Service:

Dealership Inspection & Service Items
At Least Twice A Year
Steering and Suspension Inspection:
Tire and Wheel Inspection:
Exhaust System Inspection:
Rear Axle Service:
Brake System Inspection:

GM Oil Life System
Your vehicle has a computer that lets you know when to change your engine oil. This is not based on mileage, but on engine revolutions and engine operating temperature. When the computer has calculated that the oil needs changing, the GM Oil Life System will indicate that a change is necessary. The mileage between oil changes will vary depending on how you drive your vehicle -- usually between 3,000 miles (5 000 km) and 10,000 miles (16 000 km) since your last oil and filter change. Under severe conditions, the system may come on before 3,000 miles (5 000 km). Never drive your vehicle more than 10,000 miles (16 000 km) or 12 months (whichever occurs first) without an oil change. Use engine oil meeting the GM Standard GM4718M.

The system won’t detect dust in the oil. So, if you drive in a dusty area, be sure to change your oil and filter every 3,000 miles (5 000 km) or sooner if the CHANGE OIL SOON message appears. Remember to reset the system whenever the oil is changed.

How to Reset the Change Oil Soon Message
To reset the CHANGE OIL SOON message after an oil change, do the following:
1. Turn the ignition to ON and with the engine off.
2. Press the TRIP button so the OIL LIFE percentage is displayed.
3. Press RESET and hold for two seconds. OIL LIFE REMAIN 100% will appear.

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DISCLAIMER: While Corvsport.com makes every effort to ensure that this information is complete and accurate, you should always consult the manufacturer of your vehicle if you have a specific issue or question.
1991 Corvette Fluids/Lubricants

Engine Oil: Use SAE 5W-30. However, you can also use SAE10W-30 if it’s going to be 0 F (-18C) or above. The engine requires a special Engine Oil meeting GM Standard GM4718M. Oils meeting this Standard may be identified as synthetic, and should also be identified with the American Petroleum Institute Certified For Gasoline Engines starburst symbol. However, not all Synthetic API oils with the Starburst symbol will meet this GM Standard. You should look for and use only an oil that meets GM Standard GM4718M.

Engine Coolant:  50/50 mixture of water (preferably distilled) and GM Goodwrench DEX-COOL or Havoline DEX-COOL (orange-colored, silicate-free) antifreeze
conforming to GM Specification 6277M.

Coolant Supplement SealerGM Part No. 3634621 or equivalent with a complete flush and refill.

Hydraulic Brake System:  Delco Supreme 11 Brake Fluid (GM Part No. 1052535 or equivalent DOT-3 brake fluid).

Hydraulic Clutch System: Hydraulic Clutch Fluid (GM Part No. 12345347 or equivalent).

Parking Brake Cable Guides: Chassis lubricant (GM Part No. 1052497 or equivalent) or lubricant meeting requirements of
NLGI Grade 2, Category LB or GC-LB.

Power Steering System: GM Synthetic Power Steering Fluid (GM Part No. 12345866 or 12345867 or equivalent).

Manual Transmission: Manual Transmission Fluid SAE 5W-30 (GM Part No. 1052931 or equivalent).

Automatic Transmission: DEXRON-III AutomaticTransmission Fluid.

Key Lock Cylinders:  Multi-Purpose Lubricant, Superlube (GM Part No. 12346241 or equivalent).

Manual Transmission Shift Linkage: Chassis lubricant (GM Part No. 1052497 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category LB or GC-LB.

Clutch Linkage Pivot Points Engine Oil

Floor Shift Linkage:  Lubriplate Lubricant aerosol (GM Part No. 12346293 or equivalent) or lubricant meeting requirements of NLGI Grade 2 Category LB or GC-LB.

Chassis LubricationChassis lubricant (GM Part No. 1052497 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category LB or GC-LB.

Rear Axle (Limited Slip Diff.):  Axle Lubricant (GM Part No. 12345977) and 4 ounces (118ml) of Limited-Slip Differential Lubricant Additive (GM Part No. 1052358 or equivalent) where required.

Windshield Washer Solvent:  GM Optikleen@ Washer Solvent (GM Part No. 1051515) or equivalent.

Hood Latch  Assembly, Secondary Latch, Pivots, Spring Anchor and Release Pawl: Lubriplate Lubricant Aerosol (GM Part No. 12346293 or equivalent) or lubricant meeting requirements of NLGI Grade 2, Category LB or GC-LB.

Hood and Door Hinges: Multi-Purpose Lubricant, Superlube (GM Part No. 12346241 or equivalent).

Weatherstrip Conditioning:Di-Electric Silicone Grease (GM Part No. 12345579 or equivalent).

Recommended oil, transmission, and all other fluids should meet/exceed the minimum requirements listed above. Current API ratings on oil and transmission fluids exceed those listed at the time the above information was originally published.
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