I'm agree with you about lead is bad, but only oldest designs of aircraft engines depend on lead (they use it as lubricant for valves, as it deposits on surfaces when gas evaporate).

Because of this, leaded gas still produced in commercial volumes.

Modern aircraft engines could work on unleaded gas, and especially Celera use aircraft diesel engine, working on basically aviation kerosene (with tiny addition of lubricants for diesel equipment).

BTW diesel add about 30% of Celera range.