Lobster gurgled happily, sounding much
like they were saying:

While we're on the subject of fuel... is there an easy way of
distinguishing leaded from unleaded petrol?

By taste.

Actually the petrol must be fairly old anyway...

What kind of "old"? A couple of years? A decade?

To be "leaded", it's going to be at least a decade old. If you suspect it
might be that kind of age, then I wouldn't go near using it. Keep it for
cleaning things, or get shot of it into the waste oil tank at your local
tip.

If it's only a year or three, then it's certain to be undeaded. Lob it in
a near-full tank, and you'll be fine.