Cleaning Exterior

[Pat Cassity]

I washed my new 2014 Flying Cloud yesterday and notified some type of Substance on on side that will not come off. It isn't noticeable until the sun hits it but when it does it looks like I have cleaned the trailer and missed some spots. I have tried re-washing and rubbing on it with a soft cloth but cannot remove it. Water beads up on and runs around it similar to wax. I can rub my fingers lightly across it and feel a difference between it and the rest of the aluminum. It appears that it left on when it was built I have tried car wash detergent and vinegar and water and cannot remove it. Does anyone have any idea of another method I might try to remove it without damaging the finish?

[ALANSD]

mineral spirits might clean it off. won't hurt the finish if you wash it afterwards

[dznf0g]

Auto body prep solvent, such as PrepSol brand.