bigfish wrote:...ad stabil every other fillup...
That sounds like only partially protected half the time? Not sure why?
As far as draining fuel, or fuel over 30 days old... Stabilized fuel is fine for overwintering and then running it out in the spring.
Coupla years back I had some hiccups and stalling after having to switch out to ethanol-laced gas. Actually stalled under the sandbar bridge and flatted one blade on my 3-blade prop. It was also starting very hard sometimes and then would flood out due to over-choking trying to get the thing to run. 40HP 2-stroke Suzuki.
I started using Marine Stabil religiously and have not even changed my plugs. The thing runs and starts fantastic. It has ever since the first tank of Stabil-treated fuel. Even last spring after not running from January 18th to Memorial Day- same half-tank of gas and it started like it ran five minutes ago. And although I probably SHOULD change my plugs, I haven't in probably five years or more. This winter, motor started like a champ February 4th after not having been run since The Frostbite.
While I am no fan of E10 fuel by any stretch, I have just decided to deal and keep doing what works.
As far as the warning to only run high test fuel- that actually might be good for land-based vehicles, but at least for 2-stroke marine engines that advice might be detrimental. Higher octane is in essence "resistance to burning" which allows certain engines designed with higher compression to actually (potentially) produce more horsepower. However, if the engine does not have the requirement for higher octane to prevent knocking (pre-ignition) (a potential side effect of higher compression), the expense of the higher octane fuel is unwarrented. Further, today's premium gasolines are formulated with "heat enhancers" which can negatively effect outboard engines while yet still not allowing any horsepower advantage due because there is not enough compression to realize a more substantial explosion of the gasoline/air mixture.
I think the main reason the farm dealer was recommending premium fuel is that when gasoline phases or breaks down, the base octane is reduced. Premium gasolines have a higher remaining octane after breaking down and also are more resistant to breaking down.
(Interesting side note: when both leaded and unleaded premium gasoline was still available, bracket racers (street-driven drag racers) used to mix 89 octane leaded regular with 92-93 octane unleaded to achieve a theoretical net octane of 95 as the unleaded premium octane was achieved by refining hydrocarbons but the leaded regular achieved octane by the lead additive. The leaded regular (probably 83 octane before the lead was added) would "give up" some of its tetra-ethyl lead and boost the octane. Or so racing chemists told us; all we knew was when we did it the pinging would stop while it continued when we ran leaded or unleaded premium- and didn't cost an arm-and-a-leg like the nitro-boosted Cam-2 racing gas did. Of course we are paying over a dollar more for 87 unleaded etha-fuel today than the Cam-2 Race Gas cost back then...)