Ok ok...
First off there is a thread on a twisted version of this topic...
Octane Boost
For the most part all octane boost is, is ethynol. Ethynol is basically achohol for gasoline. Most of your gasoline branded gas at the pump have 10% in it anyway.
This is the same way Sunoco Oil makes their Ulta 94. They take the 93 and inject more ethynol into it... pushing the octane up.
Now, yes, achohol will dry out and crack some O-rings... but not really in today's vechicles. They have better material like viteen (sp?) and many others... the world of O-rings is vast. And I'm sure the manufactures take advantage of this...
Now, they some of the octane boosts do have cetane as well. Which is what the refineries use to push 87 octane up to 93... that is also what gives 93 that o, so sweet smell. AND YES, you can smell the difference between 87 and 93...
The problem is I could keep going on the subject... digest that and just ask another question...