metalics have laquer(clearcote) flat paints dont which leaves them open to the elements more so than metalics.
your car has oxydation which is caused by uv sunlight damage, it breaks the paint down and if left it will eventually pit and allow contaminents to penatrate into the paint which will lead to rusting in the end
as said above you need to get it mopped out, this is done with a rotory machine and a various combo of pads and different grades of polishing compounds which remove the oxydation and make the surface smooth again, then a good sealant should be applyed which has uv inhibitors in it which will prevent this from happening again if kept on top of, sealant protection lasts from as little as 6months or up to 12 depending on the quality of the sealant applyed, then as said above a wax should be applyed to cap it all off so to speak.
if you get it mopped make sure the person doing it knows what he's doing and check out any past jobs if possible as a bandit will almost definatly go through your paint if hes inexperienced with a rotory on this kind of paint finish, your paint will be quite thin in places due to its age now;) and the fact it has no clearcote means caution must be taken when mopping especially on the tops of the wings and all the creeses and edges of each panel,the paint will be at its thinnest in these areas.
