I have heard this before, and asked a friend in the chemical biz. He spouted off five minutes off stuff I didn't understand, then said no. Not true, wont make a difference. On the same note, I have seen proof that more octane than you need makes less power. I am into bikes, ( A VF1000R, if anyone cares ) and have seen dyno chrts from friends showing that his bike made 4.5 horsepwer more with 87 than it did with 93. I know that doesn't sound like much, but max HP was 99, so 4 horse is a lot. Wayy off topic there arn't I? I guess what I am trying to say is that if you are not detonating, the car will run better with lower octane. I know in my last small block, VP or Avgas was the only fuel I could run, but at 14:1, what more can you ask for?( That car was why I asked about the mothballs. I couldn't drive the thing anywhere, to feekin expensive.)I hope my new BB will run on 93, but the fuel around here is oxygenated, which cause all sorts of other problems.