I just invested in a very nice 2-cycle string trimmer and I want it to last. I have always used stabilizer in my fuel for my 4-cycle lawn mower. I know that ethanol attracts moisture and the stabilizer does not let the water separate and sink, thus rusting out components. I also know that ethanol used to break down seals and fittings, but that manufacturers use better material now that are okay in the presence of ethanol.

Is using a fuel stabilizer and mixing the oil myself just as good as using an ethanol-free fuel? I have read some reviews of the pre-mixed fuels where a lack of lubrication (caused by quality control at the manufacturer plant) have caused pistons to seize up in the cylinders.

I don't care about the cost of the pre-mixed fuel as I wouldn't use much in an entire season; the question is more about the benefits and risks.

  • Your question is really about risk, and is therefore primarily opinion-based. Voting to close. (No offense.) That said, I'd prefer to mix myself using oil and stabilizer that I've selected.
    – isherwood
    Commented May 11, 2016 at 14:55
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    I am hoping to get actual experiences to show facts instead of just opinion. Hopefully, some small engine mechanics chime in. In other words, determine the actual risks.
    – Evil Elf
    Commented May 11, 2016 at 15:10
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    @isherwood I fail to see how risk is opinion-based. Either it's safe, or it's not, or it's safe as long as you use certain precautions.
    – Mast
    Commented May 11, 2016 at 19:32
  • Nothing is either "safe" or not. Everything has relative risk, and everyone makes their own decisions regarding what level of risk is acceptable. Heck, the definition of "safe" is wildly variable. What list of precautions makes that risk acceptable? It's a subjective question that allows only for subjective answers.
    – isherwood
    Commented May 11, 2016 at 19:52
  • Is ethanol damage prevented with the same effectiveness using fuel stabilizer vs ethanol-free gas?
    – Evil Elf
    Commented May 11, 2016 at 19:55

3 Answers 3


Nothing is guaranteed but I think the odds of you messing up the fuel/oil mixture yourself are greater than getting a bad batch from the factory. So I would say yes, the pre-mixed fuel is a safer bet. Also if you buy pre-mixed fuel there is less risk of water/dirt getting into your gas cans.

However I personally think it's not worth it. Buying pre-mixed fuel removes one possible source of problems but it does not guarantee trouble-free use year after year. You will still want to perform basic small-engine maintenance like emptying the fuel tank at the end of the season, checking the air filter periodically, etc.

You could do some back-of-the-envelope math to see how much it would cost you to use the pre-mixed stuff and then compare that to the cost of a new trimmer if this one does bite the dust. At a cost of $20-30/gallon it could really add up if you use the trimmer regularly.

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    I am an engineer and slightly OCD (joke here), and I have learned that if you want anything done right, you have to do it yourself. In regards to messing up a mix, I consider this impossible. I do agree with the cumulative cost vs replacement cost of equipment needs to be considered. I also worked as a quality engineer in an automotive part plant so I know firsthand how easily bad product can make its way into the consumer's hands.
    – Evil Elf
    Commented May 11, 2016 at 15:13
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    It'd be less about getting a new; bad batch from the factory... and more about getting a can with some unfortunate history, like it sat at a warehouse for 2 years, or was left inside a shed or vehicle for an extended period, and heat from solar gain chemically altered it. Commented May 11, 2016 at 17:22

Not all gasoline is the same... summer blends, winter blends, exxon brand, BP brand, etc. All gasoline is the same (fungible) in the pipeline; some gas stations have direct lines, while others rely on trucks which deliver gasoline from a local terminal. In either case, treatments are added to the fuel just prior to being sold to the user.

That being said, ethanol-free fuel tends to burn better (especially in 2 stroke engines) than E-10 (despite the additives used to compensate for ethanol). Ethanol is thin and does interfere with lubrication- so some of the additives are oils, to help with that issue. Unfortunately, quality is variable. If you search online, you can probably locate a gas station that sells ethanol-free fuel somewhere. That's going to be the safest bet.

Also, engine quality makes a difference. Please excuse the product recommendations, but Stihl makes the best weed-trimmer and Kubota makes the best lawn mower. This is not really an opinion; it is an observation of what withstood the most use and abuse from a commercial landscaping business.

  • Downvoter, I have more first hand experience with this than anyone would ever venture to guess. From copious chemical analyses of gasoline to being a mechanic for a very large landscaping business. Please, explain why you voted this answer down! Commented May 11, 2016 at 15:45
  • FWIW, at least locally for me, if you want ethanol free you need to buy the 91 or 93 octane gas.
    – Steven
    Commented May 11, 2016 at 16:34
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    most local stations don't have 93, only 87,89,91, in which case they say 91 contains no ethanol.. again this is what's available locally for me, so it likely differs by region
    – Steven
    Commented May 11, 2016 at 17:02
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    @BenWelborn What you say varies by brand. A lot. Hard for a person who buys BP only where there is no Chevron... to meaningfully compare notes with a person who has a smartphone app to find the cheapest gas. I do travel a lot and pay a lot of attention, and yes, some brands offer ethanol-free gas, sometimes marketed as their premium. Marketing really is the key to it. Commented May 11, 2016 at 17:15
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    @BenWelborn Very much possible the 91 has no ethanol. Ethanol raises octane, yes, but the underlying gasoline can have higher/lower octane rating to begin with. Premium users may be willing to pay a, well, premium, to have ethanol-free gasoline. Also, states (and countries) have varying laws as to what ethanol must be in (or must not be in), not just the federal US regulations; driving from IL to CO annually I see very different gasolines in each state (and region of state) along that route.
    – Joe
    Commented May 11, 2016 at 17:34

My chainsaw starts every time ever since I switched to the pre-mix 2-stroke gas without ethanol, even after leaving it in the shed unused all winter.

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