AVGAS

Bex.19

Whats the difference between Av gas and standard gas from the bowser?

Tell me what you already know and we can start from there.

Aromatic hydrocarbons?

What's the real story? In short, for normally-aspirated (non-turbocharged), low-compression engines originally designed for 80 octane aviation gas, autogas is a perfectly viable option that can save considerable money and -- despite what the engine manufacturers say -- won't hurt your engine. That said, there are down sides. To fully understand the issues involved, we'll need to discuss a bit of petrochemistry.

http://www.avweb.com/news/maint/187232-1.html