OK, I've spend some bucks to get my Murray carb cleaned out, and I'm told that I can avoid that problem (though it's taken ten years to happen ...) in the future by using appropriate, well seasoned gas.
I'm told (1) to use Sta-Bil or equivalent in my gas, (2) I really should use 92 octane -- the "good stuff", and (3) I was told separately to throw in some "lead substitute" as well.
So, what's the real deal here? The stabilizer is, I know, to keep old gas from gunking up the engine, but what about the others? I need a gasoline recipe for low maintenance and reliable service. I don't recall the Murray instructions saying anything about all this stuff.
The only think I've ever done was to run mine really dry at the end of the season to make sure that there is no gas left to go bad. I usually include using the choke or primer as it starts to die to keep it going as long as possible to make sure it is as dry as possible.
Rueful chuckle. Tried to put mine away for the winter, and found out my fuel shutoff valve doesn't seem to shut anything off. It turns (at least the exposed plastic tab sticking out of the plastic casting does), but apparently whatever is supposed to block the fuel line is no longer connected. Guess I'll have to drive it around in circles, grating more leaves, till the tank runs dry.
I have no less than 9 motors of both 2 and 4 stroke. Like you, I make sure I start them at least once a month. I have never used Sta-bil, nor anything over 87 octane unleaded. I keep my tanks full. A few of these motors are over 15 years old.
Running them keeps everything lubed as it should be and not allowed to dry out. I am a firm believer that leaving them sit without running them is MUCH worse than running them. But, to each their own.
A spare turkey baster will let you suck most of the gas out of small engine fuel tanks and squirt it into a gas can which you can then drain into your car's tank - unless you need it for a snoblower.
Use Stabil. It must be added to the gas when the gas is still fresh. Nothing will revive old gas and the problems it causes. Do NOT use 92 octane gas in a lawn mower! Also skip the lead substitute if your mower is newer than 1975.
Use fuel without ethanol. In Canada that means Shell Gold. Not sure about in the USA. LL100 AvGas works good too, but not easy to get your hands on if you don't have a plane.
I use the Sta-bil in a fresh container of gas in the Spring. Whenever I refill that container it gets another dose of Sta-bil.
It is my understanding on smaller engines the 92 octane is a far too rich to be used perhaps causing the engine to run too hot? And in my area finding the ethanol-free gas is getting extremely difficult.
That is all myth to me. I took out my John Deere mower I shut down last fall(I ran it until it quit running out of gas) fill some fresh regular gas, it started in two pulls. I always store 2 or 4 cycle tools after gas runs out. My chain saw when I need it feel fresh mix and it always starts within couple pulls. Weed eater is same. I don't do any thing special other than that.
Are you a mechanic? A small engine mechanic? or an engine designer?
I'm not the latter, but both of the first two. High octane is not required by most small engines, but is NOT damaging to use. The only reason I recommend premium fuel, and in particular, in Canada, SHELL premium, is because SHELL has gone on record in Canada as guaranteeing there is NO ETHANOL in their premium fuel.
Years ago, with leaded fuel, there WAS an issue with using premium leaded fuel in small engines (and air cooled engines in general) due to lead accumulation on valves and valve stems causing valves to stick. Sticking valves overheat. In aircraft engines (which I am also familiar with) designed for the old 87 octane fuel (no longer made) agressive leaning (lean of peak EGT) is required to keep lead buildup from causing "morning sickness" - or sticking valves on startup when using LL100, the universally available AvGas of today.
Lead buildup was the only thing that would damage spark plugs due to running premium fuel - and again, that is no longer an issue..
The other advantage of using higher octane fuel in air-cooled engines is you are MUCH less likely to destroy a piston due to detonation in the event you do overheat the engine under load. Not usually an issue with "L" head engines, but possible with today's higher compression OHV engines.
Just FYI, it was my lawnmower service mechanics who suggested high octane. "Oh, we always use the premium gas!" I had never heard that before myself. Sounded a bit fishy.
The business about lead substitute was from an elderly neighbor, who probably is pre-1975 in his 2-cycle universe.
Leaded fuel is NOT required (or even desired) in 2 stroke engines. Lead was required to protect the valves, which the VAST majority of 2 stroke gasoline engines do not have.
My chain saw has a pressurized (sealed) fuel tank and even if I leave it for 2 years it always starts on about the second or third pull. The weed eater and leaf blower are another story!!! No sealed tanks, and hard enough to start after 2 WEEKS of sitting.
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