Lyondell Temporarily Withdraws Unleaded Fuel ASTM Test Specification


Lyondell, one of the partners in development of a potential unleaded avgas replacement, has temporarily suspended its application for a test fuel specification from ASTM International. Lyondell, which is working with Basell and VP Racing to approve the fuel through the Piston Engine Fuels Initiative (PAFI), submitted a test fuel specification to the consensus standards organization but apparently did not get a favorable response. Curt Castagna, the co-chair of Eliminate Aviation Gasoline Lead Emissions (EAGLE), an industry initiative charged with achieving an unleaded replacement for 100LL by 2030, said the FAA confirmed that Lyondell’s fuel spec application has been paused.

“Lyondell had balloted its ASTM Test Spec and had received some negative comments, so have pulled it and are addressing the feedback and plan to re-ballot in the near term,” Castagna quoted an FAA official as telling him. ASTM is made up of industry, consumers and users of the products for which it creates standards. Members get a vote on whether the spec is approved. “The balloting process requires a two-thirds percent affirmative at the subcommittee level and a 90 percent affirmative at the main committee level,” ASTM says on its website. “These percentages are calculated from the ballot returns of official voting members.” It’s not clear how Lyondell’s submission did in the process or what the criticisms were. It’s also not clear how long the test spec submission will be delayed.

The Lyondell fuel is one of three being considered through the process as a drop-in replacement for 100LL. It is the only candidate left seeking “fleet approval” through the FAA-sponsored PAFI process. An ASTM specification is a requirement for a PAFI fuel. Swift Fuels is also seeking an ASTM spec for its fuel but is pursuing a supplemental type certificate instead of fleet authorization. General Aviation Modifications Inc. has already obtained an STC available for all piston engines listed on the FAA registry, but it will not seek an ASTM spec.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.


  1. Moving on down that road to 2030 +….

    Lycoming states that all bets are off on any warranty continuance by usage of a ” non approved fuel or lubricant.”

    Meaning, STC authorizations or not — GAMI fuel G100UL without ASTM spec in place and with a Cirrus ” incompatibility issue ” [ sealant ] ? matter hanging over their head is in a lurch and now Lyondell has pulled its ASTM spec ballot as well.
    How will Swift fare ? ♤♡♧◇

    • Based upon what are you making this statement? Science? Actual experience? Engine tear down? Tank and component inspection after many hundreds or hours? Ever notice how UND, Lycoming, Cirrus etc. just made statements but will not show the data on their “conclusions”! Oh no! The sky is falling … but I can change my tune if you pay me!

    • Lycoming Service Instruction 1070AB has approved UL94 which meets ASTM D7547 for use in my O-540A4B5. This is Swift’s UL94. It’s unleaded, it meets an ASTM spec and it’s approved by the engine manufacturer. If I could find it locally, I’d run it today (well this weekend).

    • Forget the engine; there needs to be long term testing of new fuel blends in older airframes and fuel systems. Honestly, the liability concerns alone should scare off anyone trying to sell “new fuels”.

  2. Switching over to a non-leaded fuel in the aviation fleet may be harder than in the automotive world? Old cars wear out and are replaced on a much shorter timeline than airplanes. Whatever fuel is ultimately approved will THEN have to prove itself in the real world of aviation where engines are often many decades old. I liken it to the imposed switch to EV’s. Just because someone waves their ‘magic twanger’ does not mean it can happen in the real world. Personally, I’d love UND or another large aviation organization to run G100UL and see how it goes. Maybe, the answer is right in front of us waiting for that chance? George thinks so.

  3. As a 44 yr mechanical engineer specializing in engine design and manufacturing, I have designed and built some of the highest HP engines ever made. The problem with lead is it deposits on the combustion chamber and its component’s. This is a very abrasive deposit and shortens component life. A aircraft engine (which I have built many twin turbo 550’s ) if built properly, could go way past TBO with unleaded fuel because it is a much cleaner burning fuel. 100 octane unleaded fuels have been around for many years. I have tested one of the fuels for one of these players trying to get the piece of the pie. It is all politics!!
    When money is to be made and possibly taken away from a company that has had a monopoly on a market, they will tell everyone the other guy is going to kill your engine with their products. I say BS!!
    Gami has a fuel that has been engineered and works. They just beat the big boys at their own game!

    • The last couple of sentences of Bretcon’s post is KEY to this issue. GAMI developed an FAA approved fuel but the “big boys” are upset because they are not getting any money…so they are coming up with nonsensical “rules” and horror stories. Meanwhile, planes are being flown for hundreds of hours with GL100UL with zero problems. Cirrus came out with their doom and gloom of “you use it and your warranty is voided”…guess what engine that GAMI used for their test stand operations? I am not an engineer, nor do I have any interest in GAMI monetarily but I will gladly run their fuel through my Bonanza every day all day.

    • Exactly – the reason why modern car engines go 100k miles between tune-ups and have extended oil-change intervals is only partly because of their modern technology. A big part is because they run on unleaded gas.

      Modern car engines wouldn’t last as long or be as reliable if they still had to use leaded gasoline.

    • Amen! Tetra Ethyl Lead, has no value in and of itself, it was a means to an end during WW II. An effective, cheap way to increase power in combat. What current av motors must have is; low vapor pressure, materials compatibility, storage stability and reasonable octane etc., SOME av motors also need high octane. Eliminating the TEL will allow ALL those motors to run without lead fouling on plugs, ring lands, sludge in the oil etc. There is a good reason that Rotax doubles the service intervals when running lead free.

      Now, a different question is whether Lie & Con motor companies have been selling “improved” cheap low spec valve seats for decades that unleaded fuels (or just close monitoring) may reveal. If they know their valve seats where not in fact, brought up to modern standards, there would be considerable reason for them to protest loudly against any move away from a fuel that just might barely be keeping their weak materials from being targeted by mechanics and owners.

    • Many aircraft engines now go way past TBO already running leaded fuel, sometimes twice TBO, all pilots should look up the incredible work of Mike Bush on TBO and more, it could save you lots and money and other valuable things.

      This is a complicated issue as any aviation fuel not only has to preform in the engine in a incredibly demanding environment it has to be compatible with fuel cells, tank sealants and all fuel system components and STABLE in contact with all that for months and months at a time, in all aircraft and in some that are pushing 100 years old!

      Testing a new fuel completely under all those variables is really not possible so there is going to be some level of user beta testing in the field… and the air , so sign here and please step forward to volunteer.

      Also don’t discount the pressure that the FAA has to be getting from higher up on approval of a “greener” UL fuel, after all we are talking about a current Federal government that is in the process of banning gas powered vehicles and appliances!

      • What’s all this talk about the Titanic going too fast. Its the gov’t that’s trying to slow us down. After all, the Titanic is unsinkable.

  4. “ASTM is made up of industry,….”

    And therein lies the problem – the industry that currently profits from selling leaded avgas gets to vote on the replacement.

    When an outsider comes along with a new formula that threatens your current profits, which way would YOU vote?

    That’s what GAMI is trying to avoid by going with an STC vs ASTM. Looks like Swift will do the same thing.

  5. This ASTM spec smells of self interest from beginning to end. I just hope GAMI/Swift/Lyondell have the deep pockets to challenge and win against “the self-interest establishment” and their propaganda.

  6. “Lyondell had balloted its ASTM Test Spec and had received some negative comments, so have pulled it and are addressing the feedback and plan to re-ballot in the near term,”
    So they are proposing their own spec? So are the other players proposing their own specs as well? That appears to be the case. Why isn’t ASTM testing the fuel to the existing spec? The one, if I remember correctly, GAMI claims 100LL doesn’t actually meet.
    It appears the entire EAGLE program may be running down the same path as PAFI, spending a lot of money and getting nowhere.
    Where are the current 100LL companies in all of this? Unleaded fuel will make their product obsolete. One would expect them to get into the game, unless they are waiting for another company to do the research and they just produce the fuel, no development costs for them.

  7. Help me out here, I don’t know anything about petroleum engineering. If the lead is removed from 100LL, apparently we have 91 octane. I don’t know if these companies are developing whole new blends, but it seems logical to start with the present recipe for 91 and develop from there. The present blend stores so well, it seems problematic to deviate much from that. Maybe that is the process that is ongoing, but it seems we are making this too hard, especially with all the smart people on the planet.

    • As I understand it, avgas without lead can only be around 94 octane. Much research was spent on trying to find another chemical to ‘simply’ replace the lead additive and get the same octane boost, but without success. Other chemicals either didn’t boost the octane enough, or didn’t store well, or attacked materials, or left too many deposits, or….

      Even ‘lead’ is not without side-effects. Additional chemicals have to be added to gasoline in order for the lead to leave after doing its job. It’s a surprising number of chemical reactions that have to occur in order, at the right temperatures, during each combustion cycle, in order for (most of) the lead to exit with the exhaust and not deposit on pistons, valves, etc.

      Now, ‘gasoline’ is not a single chemical. It varies depending upon the crude oil used and the refinery, but a ‘typical’ sample might be:
      4-8% alkanes;
      2-5% alkenes;
      25-40% isoalkanes;
      3-7% cycloalkanes;
      1-4% cycloalkenes;
      20-50% total aromatics (0.5-2.5% benzene).

      GAMI (and others) had to look for a mix that, when blended together, had a ‘naturally’ high octane even without lead or any other octane boosters. GAMI used many of the same chemicals already present in the refining industry, but mixed in new proportions. The result is G100UL, first developed in 2009. It’s been tested for hundreds of hours on a test stand, more hundreds in actual flying planes, and stores at least as well as avgas (three-year-old samples still test as good as new). It actually has a higher octane than the current 100LL.

      The UND flight school ‘valve-recession’ issue is interesting because the ‘unleaded’ fuel they’re using is essentially avgas without the lead. Much has been made of the fact that removing the lead ’caused’ the valve recession. But unleaded avgas is not 100 octane anymore, it’s only 94 octane. And the engines used by UND were originally certified as needing 100 octane. Lycoming later amended the TC for the engine by saying 94UL would be ‘approved’, but speculation is that the engine would then be running on the ragged edge of detonation… which can cause valve recession.

  8. Piston GA is a relatively tiny segment of aviation dollars. Being so tiny and insignificant, it of course naturally has to fragment itself into even tinier pieces. Each tiny fragment is out for their own self-interest. “Freedoom”, indeed. Playing musical chairs on the Titanic does none of us any good, and, if it keeps up, we’ll all go down with the ship.

  9. If I am not mistaken, the original research and development for the G100UL was done by the US military for a post WW2 unleaded fuel for the big bombers. I think GAMI took the recipe, tweaked it to make it the best for the modern world, and then started testing the snout out of it.

  10. With some members of the EAGLE board recently having their integrity questioned, should they be in a position to pass judgement on these issues.

  11. Teem doesn’t look like the ASTM route is working out to well.

    Probably since it’s just another government program looking for extended funding (2030 anyone, anyone?) researching a problem that’s already been solved.

    Now Swift Fuel is going the way of an STC, never saw that coming!

    Wise up, you’re getting played by AOPA, FAA, EAGLE, PAFI and the big oil companies.

    G100UL is the solution and the future, unfortunately it will cost more, to the detriment of GA, at least initially.

  12. Lets require UL94 everywhere so we can get the process started. Besides I am not happy with all the damage I continuously get from using leaded fuel in my Cessna Skyhawk.

  13. Given the daunting ASTM approval process and the negative feedback received, Lyondell’s temporary withdrawal of their test spec might seem like adding water to a mud puddle—making an already messy situation even messier.