Hi Jerry - Not sure if you know this, but there is a small company up in Ada, OK called GAMI who have been working on this problem for years, and they appear to be onto something. Rather than wait for the FAA to certify a replacement fuel in 2018, GAMI is working toward receiving Supplemental Type Certificates (STC) for each airplane and engine type out there to use their blend. Embry-Riddle University in Florida has been testing the fuel and have so far reviewed the results favorably. I linked to an article about it below, which is about a year old. I sent GAMI and email today asking about their progress, and they replied (promptly) that what they can say publicly hasn't changed much, but that the Embry-Riddle testing is almost wrapped up, and that the results so far have been, "very, very good". If GAMI's G100UL fuel blend actually comes to fruition in the market, it will be a real win for GA. And let's hear it for the little company in Ada besting big oil at their own game! -Glen Embry-Riddle: GAMI G100UL Tests Looks Promising - AVweb flash Article
