I took 3 gallons of 4-6 mo old 2 cycle gas and put it in my explorer...
Luckily it was under warranty as it clogged up a couple injectors... Not
sure how or why or if it was a total coincidence but I won't do it
again....
I do dump it in my carborated 125 HP Merc and have never had a problem.
No smoking or anything but the most I have dumped is 3-4 gallons
into a 50 gallon tank.