On 06 Sep 2018, dpb wrote in alt.home.repair:

W/ an engine that's never run leaded, probably ok, years ago in
days before unleaded neighbor borrowed my lawnmower and dumped a
bunch of Coleman fuel in it...it dissolved all the lead
accumulated deposits and completely coated the inner workings with
the remnants--trashed the engine completely.

Even w/ new I'd dilute it 10:1 or greater to get rid of it.

I think this will be my solution. I'll just dump a few ounces of it in
my mower and car when filling the tank until the stuff is used up.