I grabbed the string trimmer, which always starts on the 4th pull, and pulled the rope about 50 times. My wife called from across the yard, ever so sweetly, "Did you put the new spark plug in it?" Furious at the (expletive) trimmer, I positively BELLOWED back at her, "OF COURSE I PUT THE ... oh." 8-)

I'm not advising on Stihl 2 stroke 89 octane fuel requirements - I'm just reading the label. I figure the Stihl engineers know more about which octane to use than I do. For the sake of twenty cents extra a month, I do what they recommend.

If memory serves, (and that's always questionable for me), the Stihl 89 octane labeling first appeared a year or so ago?

Just some random thoughts

Stihl brand 2 cycle oil requires the use of 89 octane (mid grade) fuel.
Some claim the higher octane burns a little cooler. Not sure.

Ethanol is essentially alcohol. Alcohol readily absorbs water. Almost every gas tank is susceptible to condensation. Stale ethanol gas = problems.

I was mf'ing my snowblower 2 years ago. Alas it had the illusive "key" in the off position. I will reluctantly mention it may have been after a few beers also.

Being low lead would it harm my mower or gas trimmer?

Regular gas is absolute crap! If they bump up the amount of ethanol added to regular, the refiners only have to produce about a 80 octane fuel.

All of my small engine stuff starts MUCH better with high test. Even better with AV gas, which I sourced last fall. I don't use the better gas for more power, I got tired of the poor starting, gummed up carbs, having to keep chokes on to run, etc. And fyi, 2 things. I counted the other day, I have 16 pieces of small engine equipment that I use regularly. And, I used to always use fuel stabilizer. Made zero difference.

So, I threw in a few tankfuls of premium in my minivan. I used it for a few months and got about 10 to 15% better fuel economy, depending upon usage.

So, essentially, we're paying premium fuel prices for gasoline that was labelled as regular a few years ago. Yea.

quote:

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Using high-octane gas in a car designed for regular accomplishes little except more rapid combustion of your money. Some refuse to believe this, claiming, for example, that premium gives the family Toyota better mileage or more power. These people are in dreamland. Others say premium is purer or contains detergents that will cleanse your engine of uncouth deposits. Likewise misguided thinking--government regulations require detergents in all grades of gasoline.

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quote:

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Energy content: fuel ethanol contains around 33 percent less energy content than regular gasoline. The energy content of gasohol blends (E10 or E85) is determined by the energy content of ethanol and gasoline, and their ratio.

Engine power and fuel economy: The engine power and fuel economy are determined by the engine configuration, the efficiency of an engine, and volumetric energy content of the fuel used by the engine. For the same engine type and efficiency, the difference in fuel economy depends entirely on the volumetric content of the fuels. Due to the low energy content of ethanol (Table 1), E10 has approximately 2 percent lower mileage than regular gasoline. For example, a car averaging 30 miles per gallon (mpg) on gasoline would average 29.4 mpg when using E10. However, when using FFV running on E85, the mileage will drop significantly (10 percent to 15 percent lower than gasoline). A Consumer Reports article in the October 2006 issue reported on the poor fuel economy of FFVs fueled by E85. Currently, major automakers are optimizing their FFVs to run E85 more efficiently.

»pubs.ext.vt.edu/442/442-884/442-884.html

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I don't know where you are but here all grades are labeled 10 percent but that varies all over the place from 5 percent to 20 percent. The 20 percent is causing all kinds of grief to those buying it.

the problem is, if regular has ethanol in it, it has only 76100 BTU per gallon. so you'd get more power with premium without the ethanol. ethanol was a stupid idea anyway, so much corn is diverted to making that, that feed prices have gone way up, and increased the meat prices for anything that eats, or has corn as part of it's food.

REGULAR VERSUS PREMIUM GASOLINE

Regular Gasoline Has As Much Merit As Premium Gasoline

There is little difference in energy content of regular versus premium gasoline. They both contain about 111,400 British Thermal Units of energy per gallon.

Using the fuel stabilizer is a good practice. Been using it for years with good results. Right now I'm using fuel I mixed last fall in my trimmer and blower.

From Scientific American:

Fact or Fiction?: Premium Gasoline Delivers Premium Benefits to Your Car

Exploding the myth that premium gasoline delivers better performance in the average automobile

In most of the U.S., regular gas has an octane rating of 87, midgrade gas is 89, and premium is 91 or 92. (Octane ratings are lower in the mountain west due to the effects of thin air on internal combustion.) Contrary to widespread belief, the octane rating doesn't indicate how much power the fuel delivers; all grades of gasoline contain roughly the same amount of heat energy. Rather, a higher octane rating means the fuel is less likely to cause your engine to knock or ping. Knock, also known as detonation, occurs when part of the fuel-air mixture in one or more of your car's cylinders ignites spontaneously due to compression, independent of the combustion initiated by the spark plug. (The ideal gas law tells us that a gas heats up when compressed.) Instead of a controlled burn, you get what amounts to an explosion--not a good thing for your engine. To avoid this, high-octane gas is formulated to burn slower than regular, making it less likely to ignite without benefit of spark.

What's the difference between premium and regular gas?

I too doubt the mower cares about the octane but, at least around here super/premium/hi-octane is ethanol free. While regular and mid grade "may contain up-to 10% ethanol." That's the only reason I use it in my mower and trimmer. I'd like to think by now small engine manufactures have learned to deal with ethanol but it's cheap insurance.

Leaving the kill switch in the "kill" position is a good idea when there is any chance that children might try to play with it. Of course, letting it run out of gas is an even safer option :-)