Re: Gas Selection ??
Lower octane burns hotter and cleaner, but it depends on the compression of the engine more than anything. More compression equals more power other things equal. Modern cars run more because of better combustion chamber design, extensive electronics, even variable valve control. Some will make more power on premium because they sense it and advance the timing more, a few cars require it. For a 2 stroke OB it depends on how stressed it is and when it was made. For example some larger OB older than the mid 70s do have higher compression (such as the larger Merc inlines, but many had newer low compression pistons fitted) and the manufacturers later recommended lower timing advance and many people say run premium also just in case. A newer motor I would use what is recommended providing it is stock motor. And old motor I would research, however most are not that stressed or don't have a history of pre-ignition issues. Near anything from the late 70s and newer should not have an issue with fuel octane, unless it is a performance motor of some kind then it may. Most all of those were not really available to the public.
Most lawn equipment has very low compression and can run on about any fuel, even year old fuel. Even if it runs poorly most small engines are not stressed and don't care at worst you end up slapping a new headgasket on it. Not a good idea with an outboard though, always run fresh fuel they run WOT all the time and need to run properly. But for most all equipment/motors if it was made for X fuel, that is fine to run in it. Very few manufacturers make a mistake there. Running higher octane when you don't need it is a waste of money and the engine will often run worse unless it has the electronics like some cars to take advantage of it. It may not run worse enough for you to tell the difference, but it will carbon up more. Cheap fuel will burn faster, more complete, and cleaner than high octane. There is no point in using more octane unless you have high compression thus requiring it.
