Depends how bad the paint is Turtle wax has a couple different compounds you can get either the black bottle polishing compound or the heavier grit green bottle rubbing compound just be careful with that one and put a good wax on it after. Won't take to much to get it shined up either
As paint gets old it continues to "off gas", that is it slowly lose its solvents that made it liquid in the first place. When this happens you need to replace the solvents. WD 40 is not a bad choice. Most finish restorers use silicone, these can make it difficult to paint over in the future. Add the solvent back until it will not absorb any more, then lightly polish off some of the oxidized paint, then wax.