Search for unleaded avgas should turn to Sweden

The U.S. government’s sputtering search for an unleaded fuel for piston-powered general aviation aircraft should focus on Sweden, where the stuff has been made since 1991, says Lars Hjelmberg, founder of Sweden’s Hjelmco Oil. In a report at, he contends that more than 90% of the world’s piston aircraft can safely use his unleaded fuel, called 91/96 UL.


  1. Kent Misegades says

    Note also that lead-free, ethanol-free mogas is in widespread use in Sweden and in other European countries for a large percentage of piston aircraft that require neither 100LL nor Hjelmco’s aviation-specific fuels.

  2. says

    As I pointed out in the comments section of that article, it is pretty ironic that Hjelmco’s gasoline products aren’t really unleaded, the have TEL in them, because they are ASTM D910 products. Granted there is much less TEL that 100LL but they are still a leaded avgas and I wonder what Lars will be selling when the single producer of TEL in the world stops making it? Neither Hjelmco nor any producer in the U.S. makes a truly unleaded avgas to any of the specs available, ASTM D6227 which is 82UL or 87UL, ASTM D7547 which is 91UL or ASTM D7592 which is 94UL.  ASTM D6227 is the only avgas spec approved in any TC’d U.S. aircraft, and its approval is through the STC process.

    • Lars Hjelmberg says

      Dean – the Hjelmco 91/96 UL was without any intentional added lead
      for many years until ASTM added lead as mandatory additive in their standard and we had to comply!
      The lead content is however so small so it meets the requirements of beeing
      unleaded. So an unleaded AVGAS must not be free of lead and that is the same for unleaded car gasoline. Actually lead is present in crude and follows the stream all the way down to the pump and that includes  unleaded MOGAS D6227,

      At the end Hjelmco unleaded AVGAS 91/96 UL will work fine when the TEL producer stops producing.  By the way Hjelmco 91/96 UL meets and superceeds the requirements of standard D 7547 unleaded grade 91.

      So let,s be honest.

      • says

        Why are you accusing me of being dishonest?  You admit that your fuel must have TEL in it to meet the D910 spec.  I pointed out that it was a minuscule amount.  Where was my dishonesty?

        My point was that if Innospec stops making TEL, or TEL is banned somewhere, where you sell your product, you will not be able to sell it as a D910 fuel.  You now claim that your fuel meets D7547, 91UL.  Good, why don’t you remove the TEL and sell it as D7547?  I understand that has been approved for TC’d aircraft in Europe and England, although I don’t know why that spec was approved when it was clearly a DOD spec for their drones, not a GA spec.  The GA spec is D7582 which is 94UL, but it is not yet approved by anyone to use in TC’d aircraft.

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