2003 Chevrolet Corvette Owner's Manual - Page 275

Rear Axle When to Check Lubricant Refer to the Maintenance Schedule to determine how often to check the lubricant. See Part C: Periodic Maintenance Inspections on page 6- 1 1. To get an accurate reading, the vehicle should be on a level surface. If the level is below the bottom of the filler plug hole, you'll need to add some lubricant. Add enough lubricant to raise the level to the bottom of the filler plug hole. What to Use To add lubricant when the level is low, use SAE 75W-90 Synthetic Gear Lubricant (GM Part No. 12378261) or equivalent meeting GM Specification 99861 15. Tocompletely refill after draining, add 4 ounces (118 ml) of Limited-Slip Differential Lubricant Additive (GM Part No. 1052358) or equivalent. Then fill to the bottom of the filler plug hole with the Synthetic Gear Lubricant. How to Check Lubricant 5-46