I hate those things! If they are on for to long I cant get them off unless I wetsand. Even D300 could not touch it sometimes.
If it is artillary mold,its a PITA. Ive had to wetsand on some and got very lucky at times with PowerGloss or 1Z Intensive Paste and then the usual follow up polishes. VERY lucky with the latter. BTW
What i use is Autosol metal polish in the paste form. A little dab on a spot and gently work in until it is dissolved and wipe away. On soft paints be ginger and if needed,polish away any marring left over.