Antifreeze is diluted ethylene glycol or diluted propylene glycol, which are both diol alcohols (has 2 OH groups). Glycerine or the other name glycerol is a triol alcohol (has 3 OH groups). The chemical reaction between all three sugar alcohols with Potassium Permanganate would be similar. I am not sure what the percentage of water in the diluted ethylene glycol is required to stop the reaction. The ambient temperature would also have an effect. What I would do if the antifreeze was quite diluted would be to add some sugar (if available) to the solution to turn it into a sugary syrup. As for the LEO finding some Potassium Permanganate during a search, I don't know, is this chemical restricted because of the its use in methcathinone production. Is Potassium Permanganate a proscribed illegal chemical in the US? Would the LEO really arrest you because you had some purple crystals in your FAK? Do you think you could bribe the LEO with a cure for his itchy toes or would get you into more trouble?. Do LEOs in the US have a sense of humour behind those silvered sunglasses

I completely agree with you. A box of 'every day' Lucifer matches is much more preferable than fire starting with chemicals in a small bottle. Its just that Potassium Permanganate is a really useful chemical to carry in a PSK because it has multiple uses.