"mm" wrote in message
...
Is it legal for a vendor to put kerosene in a plastic gasoline can?
(I assume the opposite is illegal, but I don't know about this.)

Is there any other reason not to put in in one?

If after I've emptied all the kerosene and want to use it for
gasoline, if there's a little bit of kerosene still in it, will that
be a problem for a lawn mower or a car?

I don't know if it is a law, but gas cans are red, kero cans are blue. This
avoids potential problems from mix-ups. Putting gas in a kerosene heater
can be a disaster. It is legal to use a plastic can. If a slight residue
is left, it will easily mix with gas and you'll never see a problem in a
mower or car once diluted.