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> It is a concern with older vehicles

This hasn't been true since about 1970, and even then, it was dubious.

That only applies to car engines; aviation piston engines evolve much slower and commonly required leaded gasoline til recently - specifically for the lead content, beyond the anti-knock properties. Most common avgas is 100LL, with significant (if reduced) lead content.

Cf. >Lycoming provides a list of engines and fuels that are compatible with them. According to their August 2017 chart, a number of their engines are compatible with unleaded fuel.

>However, all of their engines require that an oil additive be used when unleaded fuel is used: "When using the unleaded fuels identified in Table 1, Lycoming oil additive P/N LW-16702, or an equivalent finished product such as Aeroshell 15W-50, must be used."*

https://en.wikipedia.org/wiki/Avgas

Aircraft piston engine makers like Lycoming and TCM have never provided any actual evidence that unleaded avgas increases engine wear. Their assertions that leaded gas provides lubrication are anecdotal and borderline superstitious. TCM pretty much admits this in its literature:

"Field experience has determined the use of unleaded automotive gasoline to be the cause of premature cylinder replacement due primarily to rapid and severe valve seat recession." [1]

They don't ever present evidence from controlled testing that backs up their "field experience". And controlled testing of automotive engines has shown that leaded fuels don't provide any significant protection. [2]

Twenty years ago, aviation writer John Deakin issued a challenge for anyone to provide good evidence that leaded avgas prevents engine wear [3]. As far as I know that challenge was never met .

1 - https://web.archive.org/web/20171004135916/https://pceonline...

2 - https://archive.epa.gov/international/air/web/pdf/vsr-finald...

3 - https://www.avweb.com/features/pelicans-perch-55lead-in-the-...

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