What gear oil 1963 Chevy Impala?

For a 1963 Chevy Impala, the recommended gear oil is typically a GL-4 or GL-5 rated oil with a viscosity of 80W-90 for the rear differential. If the car has a manual transmission, a lighter oil, such as 75W-90 or even 30-weight motor oil, may be used depending on the specific transmission type. Always consult the owner's manual or a knowledgeable mechanic for the best recommendations based on your vehicle's specific configuration and usage.