6 months????? whose petrol do you guys buy?
The seagull will run on pretty much anything you pour into it's tank(*), and the Mariner will likely be only marginally less fussy.
I've run a twin pot carbed Johnson 25 on fuel that turned out had been sitting for over a year, and it fired second pull. Granted it was slightly more smoky with the old fuel, (I assume due to evaporation of the petrol side of the mix) but it still ran.
Any premix engine below about 5 hp will have one cyl, one carb and one mechanically induced spark. No emissions monitors to shut it down coz you are killing the rainforests, just give it a shake to make sure the oil / fuel hasn't separated out.
* figuritively! It will be a lot less fussy than a modern 4- stroke, but don't try & run it on dirty dishwater or something equally daft. I include this "state the obvious" so that in 20 years someone searching the forum doesn't do something stoopid!