The Bizarre Economics of Premixed vs DIY 2-cycle Engine Fuel

I recently bought a Stihl blower and weedeater. My dad had a Stihl weedeater that lasted 14 years. Of course, there was a lot of repair work done on that machine over its lifetime—rebuilding the carburetor, replacing components, etc.—but the point is that it survived heavy use and abuse and kept on zinging.

Like many things, if it worked for your dad, it’ll work for you. He’s been able to prove whether a tool works for the long term.

When I bought the blower and the weedeater, the sales rep told me I could double my warranty from two years to four if I bought either a) 1 gallon of premixed Stihl MotoMix® fuel or b) a six pack of Stihl brand oil to mix my own fuel. I am generally not a fan of extended warranties on most things because they tend to be a money racket.1Buying extended warranties is like gambling in Las Vegas: Do you really think you’re going to beat the house? You spend $10, $20, $50 or more to increase the length of the warranty, and the idea that the item will break within the warranty period and the cost replacing or repairing the item will be covered by the manufacturer or warranty company. The companies who offer extended warranties must know that if they sell enough extended warranties, they will have enough cash to cover the number of claims while still making a profit. I fail to see how the consumer really benefits from these premiums. I much prefer when companies build their product to last and back them by an extended warranty that highlights their confidence in their own product. Tekton tools and Uplift desks are two such products that come to mind

But in this case, it was a no-brainer to buy the engine oil because I needed it to run the machines. Even though it may have been a little cheaper to get no-name oil from a big box store, I was already at my local dealership and buying the oil on the spot would save me a trip. The doubling of the warranty was simply an additional incentive to buy something I already needed.2In my opinion, the option to double your warranty by buying Stihl oil or fuel is a very clever bit of marketing strategy from Stihl. They took what is typically a fear-based purchase (i.e., buying an extended warranty), looped it into a very practical and necessary purchase (i.e., buying fuel or oil), and ultimately made extending the warranty more about brand loyalty instead of abstractly worrying about a catastrophic equipment failure at some unspecified time in the future. Plus there’s the subtle but very powerful suggestion that the manufacturer makes the best fuel and/or oil for their machines. The latter is pure marketing and positioning—in other words, it’s a bogus claim—but its power is undeniable.

My 1-gallon gas can. Notice the 50:1 marking near the nozzle.

Both the blower and weed eater are 2-cycle engines that run on a 50:1 ratio of fuel to gasoline.3Most small engines for things like blowers and weed eaters are 2-cycle, meaning they burn a mix of fuel and oil. The common ratios are 50:1 and 40:1. 4-cycle engines are found on tools like lawnmowers, burn straight gasoline, and have a separate fill spout for oil.  Each of the oil bottles in the six pack I bought can make up to 2.5 gallons of 50:1 fuel. I bought a one gallon gas can to store my mixed fuel because a smaller can is easier to tote around the yard, and it will help ensure my fuel is always fresh. I’m a renter of a house with a small yard, not a lawn care company.

The oil bottles do not list how much oil is needed for a single gallon, nor do they have clear measurement marks on the the side if you need to mix an amount other than 2.5 gallons. The assumption is that you’ll just use the right sized gas can. If each oil container had been for two gallons, the math would have been easy: just add half the bottle.

Stihl HP Ultra 2-cycle Engine Oil

But since this wasn’t that simple of a conversion, I dusted off some of my high school math, used an online ratio calculator, and ultimately determined that I needed 2.56 ounces of oil for a gallon of fuel. I measured the oil, mixed it with the ethanol-free gas, and got back to work blowing my leaves.4Ethanol is derived from corn. Most gas sold in the U.S. has up to 10% ethanol added. Ethanol-free gas is 100% petroleum based and is superior for small engines. Ethanol draws moisture into fuel over time, which can spoil the gas and wreak havoc on small engines.

After going through the trouble of buying a gas can, locating ethanol-free gas, doing math, measuring oil, and finally mixing the oil and fuel, I started to wonder if it would have been better to just buy the premixed stuff outright. Would it have been easier and perhaps more cost effective to buy Stihl MotoMix®?

So I did some more math.

First, let’s talk about the six pack of oil.

One container of oil from the six pack can make 2.5 gallons of 50:1 fuel. The entire six pack can make a total of 15 gallons. I spent $17 for the six pack.

The price for a gallon of ethanol-free fuel is $3.10, so 15 gallons will cost about $50.

The total cost of 15 gallons of 50:1 fuel using the DIY method is about $67, give or take. Taxes are not included, and I’m not accounting for fluctuations in fuel prices, but that’s a decent ballpark number.

By that math, a single gallon of DIY mixed fuel costs $4.46.

Now let’s talk about the premixed stuff.

When I looked up the cost of Stihl MotoMix®, I was flabbergasted. It costs a whopping $34.99 for a single gallon of their premium premixed fuel.5I have no idea what premium actually means in this context.

Buying 15 gallons of Stihl MotoMix®would cost $524.85, which is $457.85 more than the DIY route.

To put it in perspective, that is a 683% increase over the DIY route. That is an astronomical difference.

The table below lists out the numbers for easy comparison:

QuantityDIY 50:1 MixStihl MotoMix®Cost Difference
1 Gallon$4.46$34.99$30.53
15 Gallons$67$524.99$457.85

I could understand a premium of 20–25% percent for name-brand premixed fuel, but a nearly 700% increase is ludicrous. That is a hefty and incredibly inconvenient price to pay for convenience. But for the sake of argument, let’s talk about what makes it more convenient to buy MotoMix® versus going through the trouble of mixing your own:

  1. No math (which could be avoided with a 2.5 gallon can).
  2. No fears about botching the mix and jacking up the machine. When you buy premixed fuel, you can assume that everything is prepared to the manufacturer specifications. You don’t have to worry about your measurements being off in the slightest. You’re buying a product that is presumably consistent from can to can.
  3. No shaking is involved.
  4. No going out of your way to a special gas station that sells ethanol-free gasoline.

Ultimately, my brain can’t see the logic or wisdom of going for the premixed route. Some folks see it differently, which is why Stihl is able to charge an outrageous price for their fuel. The convenience of buying premix obscures the cost over time.

When I told my dad what I discovered about the price of DIY fuel versus Stihl’s premixed, he replied, “Most people don’t think long-term.”

My take is this: If you own an engine of any sort (2 cycle or 4 cycle), it pays to do your research, to ignore the branding hype, and learn how your machine works. The reality is that slight variations in fuel mix aren’t going to destroy an engine.6At this point it’s worth noting that the only circumstance when I think premixed makes sense is if you’re trying to resuscitate a dead engine. I once bought a small container of premixed gas while trying to get bring a well-worn Troy-Bilt weed eater back to life. Buying premixed gas helped me eliminate one key variable: fuel quality. Old gas had sat in that weedeater for a long time, and I needed to be sure that the fuel I was using to test everything was clean, fresh, and perfectly mixed. In that case, premixed fuel was a tool to help isolate and identify mechanical issues, not a typical consumable.  My dad’s old Stihl weed eater lasted 14 years, and he never broke out a glass beaker to get the measurements down to the milliliter. Engines are designed to work within a range of tolerance: We’re talking about blowing leaves and driving to the grocery store, not putting a man on the moon.

Convenience is nice, and there are many instances when convenience is worth the markup. Convenience is why coffee shops can charge five dollars for a cup of coffee that cost maybe 50 cents to make. It’s why the mechanic can charge more than double what it would cost for you to do just about any job yourself. And it’s why Stihl can charge 683% more for a gallon of fuel than the one you mix at home.

The long-term cost of convenience is staggering, and it involves more than economics. Convenience and outsourcing are inextricably linked. Buying premixed fuel outsources the need to understand fuel to oil ratios, ethanol-added versus ethanol-free fuel, and the process for mixing fuel to the manufacturer. What you gain in ease, you lose in competence and knowledge.

At the beginning of his book Shop Class as Soulcraft: An Inquiry into the Value of work, Matthew B. Crawford asks a salient question: “What are the attractions of being disburdened of involvement with our own stuff?”7Matthew B. Crawford, Shop Class as Soulcraft: An Inquiry into the Value of Work (New York: Penguin Press, 2009), 7. My response is that the promise of convenience paints a picture of a world where our stuff just works, where we don’t have to worry about maintenance or mixing fuel, and where there’s no need to truly get our hands dirty. It’s a dreamy world where we can supposedly free up bandwidth currently required to keeping things in good repair so we can focus on other things.

That picture is a mirage, and yet it’s one that people are willing to pay a lot of money for.

  • 1
    Buying extended warranties is like gambling in Las Vegas: Do you really think you’re going to beat the house? You spend $10, $20, $50 or more to increase the length of the warranty, and the idea that the item will break within the warranty period and the cost replacing or repairing the item will be covered by the manufacturer or warranty company. The companies who offer extended warranties must know that if they sell enough extended warranties, they will have enough cash to cover the number of claims while still making a profit. I fail to see how the consumer really benefits from these premiums. I much prefer when companies build their product to last and back them by an extended warranty that highlights their confidence in their own product. Tekton tools and Uplift desks are two such products that come to mind
  • 2
    In my opinion, the option to double your warranty by buying Stihl oil or fuel is a very clever bit of marketing strategy from Stihl. They took what is typically a fear-based purchase (i.e., buying an extended warranty), looped it into a very practical and necessary purchase (i.e., buying fuel or oil), and ultimately made extending the warranty more about brand loyalty instead of abstractly worrying about a catastrophic equipment failure at some unspecified time in the future. Plus there’s the subtle but very powerful suggestion that the manufacturer makes the best fuel and/or oil for their machines. The latter is pure marketing and positioning—in other words, it’s a bogus claim—but its power is undeniable.
  • 3
    Most small engines for things like blowers and weed eaters are 2-cycle, meaning they burn a mix of fuel and oil. The common ratios are 50:1 and 40:1. 4-cycle engines are found on tools like lawnmowers, burn straight gasoline, and have a separate fill spout for oil. 
  • 4
    Ethanol is derived from corn. Most gas sold in the U.S. has up to 10% ethanol added. Ethanol-free gas is 100% petroleum based and is superior for small engines. Ethanol draws moisture into fuel over time, which can spoil the gas and wreak havoc on small engines.
  • 5
    I have no idea what premium actually means in this context.
  • 6
    At this point it’s worth noting that the only circumstance when I think premixed makes sense is if you’re trying to resuscitate a dead engine. I once bought a small container of premixed gas while trying to get bring a well-worn Troy-Bilt weed eater back to life. Buying premixed gas helped me eliminate one key variable: fuel quality. Old gas had sat in that weedeater for a long time, and I needed to be sure that the fuel I was using to test everything was clean, fresh, and perfectly mixed. In that case, premixed fuel was a tool to help isolate and identify mechanical issues, not a typical consumable. 
  • 7
    Matthew B. Crawford, Shop Class as Soulcraft: An Inquiry into the Value of Work (New York: Penguin Press, 2009), 7.
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