G96 doesn't hurt the polymer frame on my G22 and M&P 9. Doesn't hurt the painted surfaces of my S&W 22-1 either. Been using G96 forever, awesome stuff.
You referring to g96 gun treatment/oil?, yes it's good stuff. The g96 nitro solvent is non chlorinated brake cleaner, or the equivalent of. It's fine on polymer frames if you are looking to degrease and strip oil/grease off. I don't use the Nitro solvent though, only the oil/gun treatment for CLP purposes.