Rubbing alcohol made with ethanol is denatured to prevent people from drinking it but ISO isn't as it's toxic all on it's own so doesn't need to have crap added to it. That Isocol has a stuff added not to denature it but to add scent. ISO is poisonous and one should avoid too much contact with the skin or breathing the fumes yet the company that makes that Isocol crap says to use it all over to refresh yourself. That's nuts.
The scent didn't remain in your oil because you didn't purge properly. It stayed because it's an oil itself with a much higher boiling point than the ISO and remained after all the ISO was gone. You basically denatured your pot oil.
I bought some RV anti-freeze that used to winterize the plumbing as it's made with ethanol so I figured I could distill it and get free booze. The crap they put in it was still there after three runs through my still so it would take a good fractional still to separate the pure alcohol out. Too bad it didn't work as that stuff is only $5/gal.
Without some sophisticated gear you are stuck with that stuff in your oil so you could make it into a salve and use it safely on sore joints but for toking it's no good. For a cheap and safe solvent 99% methyl hydrate. (aka wood alcohol, aka methanol), can be used just like ethanol for QWISO. It's not denatured and evaporates even faster than ethanol. Don't drink that shit tho as it will blind you before it kills you.