Thanks for the reply.
It doesn't have oil injection, just pre-mix the fuel. 50:1.
Since I don't get to use my boat too often, and I'm worried about thieft, and a couple of other things, I store the motor in the "trunk" of the boat, out of sight.
Yes, storing it upright is a good answer, but not the one I'm looking for.
This year I've bought "Amsoil" synthetic 2 stroke oil, which they claim I can mix at 100:1 and this will be fine for the engine, as well as pollute less.
I haven't had time to launch the boat yet, (!) so I don't know how this will work this year.