I seem to possibly be having towel staining with Opti-Clean(?) Quite the opposite experience from ONR actually since that washes out easily from everything. I'm a little concerned that a brand new bright yellowish green towel had an odd grey-brown spot on it after it was washed. Not concerned about towel, but worried about using Opti-Clean on paint based on towel staining. I didn't wash the towel right away - I think it sat a couple of days until I had enough to warrant a wash but, again, ONR just rinses right out. Just that one Opti-Clean spot on the new towel is stained. All I did was a limited test to try to clean some bug guts on a plastic chrome piece where it melted off the front grille in the rain and sat on the trim overnight. So the contamination I was trying to clean was so small and thin layer I can't see any way that it was responsible for the towel stain. So now I'm scared to use Opti-Clean on paint after that since I had a terrible experience with a completely different waterless wash product (different company) leaving dull spots in brand new clear coat where I did some spot cleaning and must have not dried aggressively enough afterwards to remove enough of the product. ONR rocks but just not sure if comfortable with Opti-Clean yet.