Hi out there,this may be of interest to some body,I had dark marks running down the van back and front and from the side of windows ,vents,I tried some house cleaner of the wife,s and guess what,it took it off without to Mutch mussel,the name of this mirical cleaner is Power Force Multi Purpose Cleaner,$1.90 at you guessed it ALDI,s,great cleaner. If this dosen,t interest you forget this message as if it wasn't here. Lance C

Thanks lance good info is always welcome, I have used the old dishwashing liquid and find that it works well also.
Frank