[02ztsian]

I think we are all giving gasoline too much credit for the ill effects we are blaming it for. Not every oil company out there has it's own dedicated refinery supplying only it's retail establishments. Many retailers (unknowingly or not) are buying from the same refinery. As for crud, isn't that why we all run fuel filters?
I also think a lot of people equate high octane with high performance, and this is dead wrong. High octane gas burns, not explodes, and it burns slower than the lower octanes. If an engine has enough compression to achieve peak performance on 87 octane then running higher octanes will not improve performance, and may actually make it run worse! Higher octane gas has aromatics (i.e. Toluene) added to the mixture to boost octane which contribute to the slower burn, and have added detergents to eliminate the "soot" left behind from burning these heavier additives. (Remember leaded gas?) So, I can see how one may believe that high-test burns cleaner, but it burns slower. The real benefit from high octane is from it's resistance to knock, allowing us to run increased boost and compression. The real test is in comparing straight line acceleration results using a variety of octanes. Or, in fuel consumption, which will show efficiency of the burn (measured distance travelled per measured fuel consumed). I think that 99 times out of 100, we can blame mechanical failure for our problems.