i always use metalic wax on my non metalic car, but its an old car so it dont really matter if it messes it up in the end, i buy metalic cos my sisters car is metalic but i dont want to have to buy one for metalic and one not for.
Metallic wax, polish etc aint as abrasive as normal paint wax/polish so if you only wanna use it too keep your shiny it will be OK but if your paint is faded and you want it to be cut back slightly so it gives a good shine I would change it. Normal polish/wax will remove the "dead" paint and bring shine back but the metallic polish/wax will not do this aswell.