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Can your Aircraft Engine run on unleaded fuel? We believe that around 70% of Aircraft can, if it were more widely available and priced to encourage its use.


"AOPA have researched each piston engine type in the G-INFO database and have done our best to establish, for each engine type, whether it can be run on unleaded fuel or not. Some of the main resources to check engine compatibility are in the links below, please use these and talk to your maintenance engineer to verify the status for your engine."

Please let us know if:

1) Your aircraft is not listed, or any other error or omission. NB: Over 1300 piston engined aircraft had no engine data in G-INFO when we did the research, in which case it won't be listed. 

2) You use unleaded fuel and the result indicates it is not approved for your engine.

3) If your result is ? then we haven't been able to find the answer.

Please use the Ask AOPA form and select the "Other" category. Let us know your aircraft registration, make and model, engine make and model and the fuel you use.

AOPA Position on Leaded Fuel

Through the AOPA Maintenance Working Group we have been keeping abreast of moves to remove lead from AVGAS in the UK, Europe and the USA. In the USA and in Europe there is a growing lobby for the removal of lead products by as early as 2025.

The AOPA UK position statement on unleaded aviation fuel can be found here.

At home, the UK Government has been noticeable by their lack of interest or involvement, preferring to walk away from the issue. But the "Green" lobby and some news organisations are starting to ramp up the rhetoric against leaded products being used in aviation.

So the Government's indifference is not going to help us in the UK if the *supply of leaded AVGAS is stopped, the UK CAA have not appoved new fuels, there is no infrastucture or supply chain in the UK. We keep beating the doors at the CAA and DfT.

*Note: AVGAS is not refined in the UK so we are reliant on refineries in Europe. They are unlikley to continue to supply just the UK with leaded fuels and of course UK Registered aircraft wouldn't be able to refuel abroad if the CAA hadn't approved the fuels for use.

However, we estimate that at least 70% of GA Aircraft are fitted with engines that can run on curently approved unleaded AVGAS, such as UL91 and UL94, it it were available, and so long as the aircraft manufacturer has also approved unleaded AVGAS.

While UL91/94 might be more expensive than AVGAS 100LL you might find that you can offset this cost by reduced maintenance costs, e.g. 100 Hour Checks, better spark plug life. And you won't be spreading lead pollution in your wake.

By increasing demand for unleaded fuel it will encourage more aerodromes to stock it and, with higher sales, it may reduce the price.

AOPA are pressing the Government to incentivise the use of unleaded fuel, not by increasing the cost of leaded fuel, where there is no current alternative, but by reducing Duty on the unleaded fuels.

We also want the UK Government to provide funding for research and development of alternative unleaded fuels in the UK, grants for aerodrome infrastructure and to incentivise UK refining. The USA have provided $10M of funding, which the UK should be able to match.

Map of UK Airfields that stocked AVGAS UL91 in May 2023 (click here if map doesn't display)

In the USA, the FAA have approved STC's for the use of the GAMI G100UL AVGAS replacement for all spark ignition psiton engines and airframe combinations, so are well on the way to seeing the end of leaded products once the infrastructure is in place and the production of the fuel has ramped up.

General Aviation Modifications Inc.(GAMI) has officially begun selling supplemental type certificates (STCs) for its G100UL 100-octane unleaded avgas, costing around $2 per Horsepower. The STC includes a very short Approved Flight Manual Supplement (AFMS) and placards to be installed around the fuel filler ports on the aircraft and one on each engine. There is a short set of routine I.C.A's (Instructions for Continued Airworthiness) and Installation Instructions for the placards. The same as any other normal STC.

For UK G Registered aircraft, if G100UL does get to the UK, AOPA would hope to push the CAA to issue a new CS-STAN for the fuel, as they have for UL91 and Hjelmco's 91UL96. This should avoid the need for expensive STCs.