Originally Posted by cubsfan51

In addition to the 2 products mentioned by OldGuyFla, another that is right up there is Meguiar's Convertible Top Cleaner:
http://www.meguiars.com/en/automotiv...e-top-cleaner/
I live in Chicago too. Between my wife and me, we have had 4 convertibles including my current Z roadster over the past 25 years, and have always driven them year-round. This nearly snowless winter is the first for the Z, but Meguiar's has always been good for the previous ragtops.