There was a tiny little gas station near me that sold what was supposed to be 100 octane auto gas from one of his tanks. He would add Justice Brothers octane booster to the premieum auto fuel he had. He got it in 15 gallon barrels. (In Mn we can get premium auto fuel with no alcohol) He sold this stuff to the racing guys in the area. Anyway, I thought I would try some in my Avid Flyer. I had just installed a new Jabiru engine in the plane and they specify higher octane fuels for this engine. Before I started to use this stuff in my fiberglass tanks, I figured I would do some testing. I had a plastic bottle that I used to test for alcohol in gas with, it was about 1" x 6" tall. I put some small pieces of fiberglass in the bottle and filled it with the souped up gas. Next day the bottle was empty. It had softened to the point were it melted the bottom out enough for the gas to leak out. I had used this bottle plenty of times before with regular car gas with no issues. Never did find out if the souped up gas was bad for fiberglass or not. The moral of this story is: be careful of what you put into the fuel tanks. I would be far less afraid of mixed gas than I would of octane boosters. JImChuk