well here,. When you take your wax pad and apply wax to the dull areas of the car, mainly lacking clearcoat, you'll realize that your wax pad will probably pick up the color of the car. Over time the problem will become worse. In this case of waxing the car it would be solely to protect the remaining paint and not as much for appearance. Pre-late 70's automobiles, mustangs and such, didnt use flat base colors like now because they didnt use clearcoats then. They used something like enamels, paints that have some sort of luster without a clear. Considering this car is black the paint could be very flat and most likely non-metallic. The majority of waxes will leave a light residue instead of the "SHINE" you need. I took automotive refinishing classes and my recommendation, depending on the area, would be to get the area wetsanded the re-cleared.