Ultimately the availability of 100-octane, leaded fuel (avgas) is governed by the continuing demand from the General Aviation sector.
No matter how thirsty warbirds are, they are relatively few in number compared with tens of thousands of Cessnas and Pipers and the like.
While they are flying, there remains a (reasonably) viable business case for continuing to produce Avgas.
The relatively low volume of Avgas production also gives it a reasonable case against environmental issues too. The major reason for the removal of lead compounds from road fuels (remember 4-star and 5-star?) was because of high lead accumulations in the atmosphere at ground level at major road intersections.
As aeroplanes fly around, what little lead-laden fumes are generated are pretty thinly dispersed. You’re more likely to get lead in your bloodstream from some Victorian piece of lead plumbing!
While diesel engines have been used recently in light aircraft, the fact that the biggest diesel engine producer is currently in financial trouble, isn’t likely to encourage too rapid a change-over from gasolene. In fact there’s a good supply reason to stay with petrol, as every other form of transport is fighting over diesel fuels, shoving the prices ever-higher!
Some modern engines such as the Rotax, are designed to run on unleaded ‘mogas’ type fuels (and in fact some vintage engines can handle it too). However there are some potential problems in using it.
It is more prone to vapour-locking at higher ambient temperatures and the recent introduction of ethanol into some ‘mogas’ supplies can potentially make that issue even worse.
Having had a vapour-lock on an aircraft engine on climbout 😮 I’m back to being a keen advocate of Avgas on my aeroplane, even if I have to clean lead deposits off the spark plugs a bit more often!
I guess if leaded avgas were to be phased out, there might be a case for adding lead compounds, as classic car owners do as ‘octane boosters’. But as the EPI article points out, some of these compounds are themselves much more toxic than lead-compunds and there would have to be a bit of testing done to ensure the additive didn’t attack fuel system or engine internals.
Although the article is alarmist – I’m sure that the financial case for ongoing production will keep supplies of 100LL going for a another 20 years at least.
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