I was told that avgas should be avoided because among the other reasons listed in that nice link(thanks Richard) there are additives to keep the fuel from freezing at high altitudes. A friend swore by avgas until the back of his pristine black GTO became discolored. We asked engine builder and aviation enthusiast Lee Bandrow and he quickly knew what it was. He scolded us like disobedient puppys and sent us on our way.
