GAMI Begins G100UL STC Sales (Corrected)


General Aviation Modifications Inc. (GAMI) has officially begun selling supplemental type certificates (STCs) for its G100UL 100-octane unleaded avgas. As previously reported by AVweb, the FAA approved STCs for the use of G100UL in all general aviation piston airplanes in September 2022. GAMI says it is looking to have the fuel available in California by mid-2023 and nationally by 2026.

“GAMI is excited to announce the opening of its online G100UL STC store,” the company said. “All gasoline powered airplanes and engines in the FAA’s type certificate database are covered by the STCs for G100UL, which is the first and only FAA-certified, totally lead free, high octane avgas.”

As with similar fuel STCs, price for the G100UL STC varies based on an aircraft’s engine and horsepower. According to GAMI, it comes out to roughly $2 per horsepower, bringing average STC cost for aircraft such as the Cessna 210, Cirrus SR22 and Piper PA-32 to the $600 range. When it comes to the fuel itself, the company says pricing for G100UL will be “slightly higher than 100LL” until production volume reaches several million gallons annually.

Further G100UL STC information is available at

Kate O'Connor
Kate O’Connor works as AVweb's Editor-in-Chief. She is a private pilot, certificated aircraft dispatcher, and graduate of Embry-Riddle Aeronautical University.

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  1. “the FAA approved STCs for the use of G100UL in all general aviation piston aircraft in September 2022”. Is this true? Their web site doesn’t list any GA piston helicopters as far as I can tell. No Bell, Enstrom, Guimbal, or Robinson, for example.

    • Edit, an STC will be written for aircraft with those engines. George Braly said the list of approved engines at the time of that interview was 35 pages long and growing, quicky.

      • No Hughes/Schweizer or Lycoming HIO-360 engines used in them yet either – fleet wide and all aircraft (“every general aviation spark-ignition engine and every airframe powered by those engines”) cannot be claimed until all piston-engined helicopters are included too. I support the effort, but need my aircraft to be included too.

    • The press release has a slight error. It says “aircraft,” but it means “airplanes.” The rotorcraft STC is in the works.

  2. I like that. The prices won’t come down until millions of gallons are sold annually. I’ll be retired before that happens, and I have at least 7 more years to go….

    • Like Karrpilot, I too see, at best, a long slog ahead given the current situation.

      Our free enterprise system is a simple yet awesome, marvelous thing and I’m a fan, but to achieve success with any product that competes with an existing one it demands that the new product must provide the customer with added value, be it real or perceived. I fear GAMI will need the heavy finger of government tipping the value scale to make a go of this.

      • I think the one thing that might tip the scales without government intervention would be the likely lower maintenance costs and longer engine life from not having lead salts in the combustion chamber, crank case, etc. I wouldn’t be surprised if early adopters find that the added cost is worth it. This won’t be immediately evident to operators, however, so the initial motivation to adopt the new fuel isn’t going to be purely economic one.

  3. GAMI wants me to purchase their fuel, but, first I have to pay them for the privilege? Doesn’t sound like they really want to sell fuel.

    • Peterson wasn’t selling fuel at all, and people still had to pay them for the use of their STC. That isn’t new. GAMI must have spent buckets of money over the time it took to get this STC. They’re selling it for relative pennies. In fact, as best I can tell, the STC price only covers their cost of maintaining the list (required of them by the FAA) of which specific aircraft have the STC installed.

      • They also supply the 337s already filled out, and the placards for the fuel fill ports and the engine. Not a huge thing, but there are costs involved.

  4. George Braly and GAMI will go down in history as one of the great aviation legends with the likes of Cessna, Beech and Piper. Finding a solution to the unleaded aviation fuel problem, and overcoming the industrial competitors and government are monumental victories.

    But the threats to GA are many and diverse. Along with the increasing and inflationary costs of airplane ownership are the long term challenges of maintenance, insurance, and parts for orphaned airplanes.

    But motivating, finding, inspiring and training the next generation of pilots poses the greatest question for the 21st century.

    Manned flight itself may be going the way of the dinosaurs given the advancement of UAS. I don’t believe we have the hardware or software yet to put R2D2 or C-3PO in the right seat of an airliner yet, but I guarantee someone’s wrinkling on it.

  5. Nice they are coming up with the new fuel. What will the price be per gallon. Does slightly higher mean $8.00 per gallon. I think many GA owners are going to have an issue with this fuel cost.

    • While the cost of any aviation fuel is frustrating, I don’t agree that everyone will have an issue with the fuel cost. You either pay it and fly or don’t fly. Additionally, there is suggestions that oil change intervals and other MX related costs driven by leaded fuel will be eliminated or reduced. Lead fouled plugs eliminated, extended hour oil changes, increased hours to overhaul, reduced fuel consumption, non aviation cost contributions ie non aviation use of the high octane fuel increasing the volume produced, reduced refinery and transportation costs due to non segregation of leaded fuels, and then the last item – complete elimination of leaded fuels with no alternative. Imaging if the EPA was allowed to ban leaded fuel with no alternative? How much is that aviation diesel engine again?

  6. I’ve already purchased the STC and have received the required documentation and placards. Now all I need is for the fuel to be available, and my local airport authority (San Mateo County, CA) has already said that they will offer it.

  7. Glad to see GAMI sending 100UL fuel to California. Maybe I’ll plan more flights West and hopefully Arizona will get 100UL soon. Don’t forget Arizona, GAMI.

  8. Except for government bureaucracy, why is an STC needed if it is approved for everything? And you have to put a tag on the engine and placards near the fuel filler, even though it’s approved for all piston engines? This is just silly FAA regs. They can’t get out of their own way. They want lead out of avgas. Somebody accomplished that, then they put a pay to play fee on it and logbook entries, placards, blah blah. Where’s AOPA and EAA on this? Why the extra stuff to do as if it is so special? It’s what everybody wants, including the FAA.