I use WC Helimix 15% and have brown spots. What gives ?
Maybe you should use a little bleach the next time you wash your skivvys. That should take care of the brown spots.
I dont have an answer for that one. I use the 30% and even though I do not wipe the muffler down I still do not get the brown spots on the muffler. Could it be from something else getting on the muffler and cooking? Can you take a picture of it?