Stan, It is Plain old 92 octane unleaded gasoline. We ran regular leaded gas when it was available up to the early 90's. I know there are other choices for fuel but this is the only fuel I have ever run in a Dyna-Jet. I have no experience with other fuels. Someone with more knowledge might fill us in on other options and how they work. This airplane was never flown in any contests, it is strictly for fun. That's pretty much why I never tried using other fuels. Using gasoline and the stock metering jet worked very well for us. Very reliable, easy starts, consistent runs. Its a very fun airplane to fly, I will post a video soon. Mike