Letter: E-85 and Generators


I didn’t have any luck searching for this on your website. May be something you consider for a future article.

How well/poorly do portable generators function using “ethanol gas” (E-10 ‘the normal mix”, and E-15 [or higher] which various lobbies seem to want to foist on us)? How about going all the way to E-85 if you can’t obtain/forage/swap for “the good stuff”? Even with stabilizers, the ethanol is very hygroscopic so goes bad fast, but what about a post-hurricane/tornado/etc. scenario where it hasn’t had to sit long in the tank?

I got to thinking in the post-Maria coverage that I didn’t know how well generators tolerated ethanol? Because it reduces the “energy density” of the fuel, would the power generated make it past the controller? Screw up your system?

I know enough to be dangerous about how it potentially affects motor/vehicle operation, but almost nothing about potential effects when you throw in power generation and trying to keep it “clean” and steady enough for modern electronics.

HJL’s Comment:

Small engines usually don’t fare very well on the oxygenated gas. Among the issues is that the alcohol is hard on the rubber hoses and gaskets. Older generators that are not made from some of the newer plastics will be destroyed in short order. However, many of the newer generators are rated by the manufacture for E-10 and E-15. As a general rule, I prefer to seek out non-oxygenated fuels for my small engines (generators, weed whackers, et cetera.) To know for sure, you need to contact the manufacture of your small engine and get their recommendation.

Most small generators die because they are not used enough and moisture from various sources (humidity, water and/or alcohol in the fuel) causes rusting issues. The obvious solution there is to make sure that you are firing up your generator at least on a monthly basis to keep it lubed and clean. Alternatively, you need to winterize for long term storage.


  1. In South Carolina non ethanol fuels are readily available, and demand seems to have expanded the number of filling stations offering it as an alternative to ethanol fuels, albeit at a premium cost. I use it in my backup storage cans and fill my small engine equipment out of said cans, then use the balance at around six months to top off vehicles before refilling them.

  2. In South Carolina non ethanol fuels are readily available, and demand seems to have expanded the number of filling stations offering it as an alternative to ethanol fuels, albeit at a premium cost. I use it in my backup storage cans and fill my small engine equipment out of said cans, then use the balance at around six months to top off vehicles before refilling them. I’ve had good luck with this even without stabilizer additives.

  3. Some of the self serve card- controlled fuel distributors stock ethanol – free gasoline. I got their cards for my family. Those places are more likely to still have fuel in a panic. And always drain your fuel tank when not using your genny. Then cover it. Check to make sure you have a fuel filter. If not, then install one. Honda generators are on special markdown prices right now. They are worth the money.

  4. I spent several day getting genarators working for my area before the last storm to hit Florida. Sitting without proper care was the cause of most failures. Older equipment may not like the E-85 but most will run just fine if the fuel system has not rotted. The governer system on most small generators do not care what fuel you put in it. If you are so inclined you can richen the fuel mix to compensate by backing out the screw that adjust the idle mix. While this is called the idle mix it richens the mix across the full range of RPM.

  5. In my locale the only thing we seem to be able to get is E10 gasolines. The generators seem to run fine if the gas is fresh but tend to have issues if we leave gas in the fuel tank for any length of time. I drain the floatbowls when done. I buy high octane and keep the full 5 gal gas cans closed up tight and in a cool location. It seems to last about year without additional stabilizers. Partial cans need to be used up sooner. About once a year I dump the cans into one of my gas burning vehicles and pick up fresh fuel for the cans.

  6. I have noticed that small engines these days may not start after a few months even if run dry before stopping. By accident I discovered that removing the float bowl and putting a rubber tipped air hose straight up into the bottom opening and giving it a few squirts of air will often clear what’s wrong and the engine will start.

  7. It possible, use only ethanol-free fuel in all small engines. In my experience, within a year of using fuels with ethanol you will face issues. Being hard to start, running rough, lower power output and general disintegration of rubber and some plastic parts are just some of the issues to be expected. If you use ethanol, plan on learning to rebuild carburetors!
    As to availability, check with smaller gas stations or convenience stores that sell gas, particularly the individually owned ones. Expect the gas to cost as much or more than premium fuel. It’s worth it!

    1. My experience differs from yours: I have a Generac 5500XL that I’ve owned 18 years. It has seldom been used for power outages, but gets a 15-minute maintenance run the 3rd Saturday of every month. I have always used E10 regular dosed with Stabil. Sometimes the fuel in the poly tank is one year old and the engine runs fine. At the end of the maintenance run, the shutdown procedure is to turn off the run switch (ignition) and immediately turn off the fuel supply; I do not run the carb dry. Next month (or unscheduled use), set the ignition switch to run, turn on fuel, engage choke, and pull the recoil starter–always starts on first pull. The difference between your experience and my experience may be due to different engine manufactures, or the quality of the materials of the fuel system. Hard to pinpoint, right?

    1. Propane is great but it will be mighty hard to scrounge in the future. I find diesel to be the best for generators and pumps as it stores well has more calories per gallon, thus longer run times per gallon of fuel and requires no high pressure tanks for storage as well as the engines last far longer. Yep the gen sets cost a lot more, I have ran them 24 hrs. per day for extended periods of time , gas engines cannot begin to compete.

  8. in regard to your monthly inspection and test running of the engine – you need to plug in an electrical device to energize the alternator part of the generator – likewise an important maintenance chore ….

  9. For emergencies and small engines I use trufuel. Home Depot carries it. It will keep your carb from fouling. I also keep a can or two in my vehicles just in case my wife forgot to fill up the tank. Of course that never happens.

    1. Same. Just wish it wasn’t $24/gal. I also traded the cost of needing to replace my new 2 stroke tools carbs and fuel lines every couple of years from ethanol failures to using true fuel. Wash in price, but less frustrating than tools randomly being broke at inopportune times. 2 is 1 and 1 is none can all too often be 2 is none with ethanol…

  10. Service stations in rural areas often have a separate pump for ethanol free gasoline. You won’t find these in town or suburbia. Check with the local Farm/Feed store, they will likely know. Expect to pay quite a bit more for it, at least 50% more.

  11. After three years in the Bush of central Alaska, we learned the importance of life without power. We had a 3kw and fuel was non eth. at that time, but we found that 50 below weather made running tough and so we learned to use power less and saved it for special occasions. Movie night with neighbors, was our weekly high light. No motor is good left unused for very long, but you will find that our ancestors were never as bored as we can be today. So try some old fashioned approaches to your power use and take care of your machines as well.

  12. There are people, a lot of people, that have been schooled that 10% ethanol gas is good. They avoid the fuel without ethanol. I was able to top off my supply while all the other pumps were out.

  13. If you are worried about ethanol in small engines, I suggest you remove the alchohol portion from the fuel before filling your equipment’s tank. To do this, simply add water to the tank you are filling from, agitate the mix a bit, let it sit for an hour or so, then pour off the pure gasoline once the alchohol/water mixture has settled to the bottom. You may need to add some octane booster as the alchohol raises the overall octane value of ethanol, and removing it will lower it a bit. Discard the alchohol/water mix from the can.

  14. I buy aviation gas at the local small airport. Ethanol free and high octane. A little more expensive but it is the best gas out there. I believe it may still have a little lead or a lead substitute in it for valve train lubrication,although don’t quote me on that. My older motorcycles were built for leaded gas as were many of the older planes flying out of this airport.

  15. Yeah, down here in FL when Irma dropped by I could still get eth-free gas at the local station after the other pumps were tagged/empty. Which was great because that’s what I normally use in my vehicle.

  16. Unfortunately, the only local sources for non-E fuel here are the community boat dock and a distributor some distance from my residence. I always use non-E in all my small engines and keep it in my long-term tank. In addition to using Pri-G stabilizer, I keep the fuel acceptably fresh by also burning it in my older truck which was made before ethanol became widespread. Refills for the large tank are accomplished by taking a 100gal tank to the distributor during the colder months (winter blend!) as needed to replenish the year’s consumption. The process is a pain but certainly well worth the effort even in “normal” times as it reduces deterioration in the gens, saws and mowers plus keeps the truck able to be topped off quickly in case relocation becomes necessary.

  17. The most important thing we discovered with small generators is not the fuel, but the maker. When we first went off grid we tried every generator you could pick up at Sears, Costco, Home Depot, etc. We literally went through a dozen of them despite not using them close to their wattage and religiously changing oil, etc Most died under 100 hours use, some lasted as long as 200. One made it to 250 roughly. To the stores credit they all took them back. But after a dozen, yes a dozen, times returning a generator and hearing ” you should have bought a Honda” this slow brained fellow finally ponied up the 3x the cost for a Honda generator and 5000 hours later it is still going along with another I picked up later with the same amount of hours. After #8 of the off brands I really started pressing the tech guys on the phone and several admitted to me they really aren’t built to do more than fire up during the very occassional power outage and if you get 200 hours on them (less than 9 days running full time) you are doing good. Until you bump up to a true industrial generator (think no wheels or true car size wheels), Honda is the only way to go for gensets.

  18. Ethanol in fuel is bad for many reasons, particularly because its ability to pull water out of the air. I have older Honda generators and they have a big problem with water in the fuel, it literally dissolves the carburetor castings in the float bowl region. I have also repaired generators that have the float bowls coated with black rubber from the fuel lines being dissolved. Often the main jet needs drilling out to get them clean. If you have this problem soak the metal carb body and parts in alcohol over night after removing any non-metal parts. This normally cleans up the black build up. Replace all fuel lines with Tygon tubing. If you do not have a fuel shut off install one in the line. This allows you to run the engine dry so there will be no fuel left in the carb float bowl. This should be done with your monthly generator exercise schedule to prevent a lot of grief when you really need the generator.
    I keep Tygon tubing in various sizes for repair of all my gas engines, you can buy it by the foot in a lot of places. Here is a tip from one of my friends that collects antique motorcycles. If you cannot get ethanol free gas you can make it. When you purchase
    fuel in your gas cans leave room to add 1/2 gallon of water. WHAT? yes I said add 1/2 gallon of water. Shake it well and let it sit, all the alcohol will settle to the bottom with the water. Decant the gas making sure you do not include any of the water/alcohol from the bottom. I buy aviation gas for all my small engines as there is no alcohol allowed in it. Cars stop, planes drop. but there will be a time when it becomes unavailable and we need to know how to make do or revert to the stone ages.

  19. I converted mine to run on propane.
    As an alternative, I go to my local small airport to buy aviation fuel. It’s got a higher octane rating and has no additives. It’s a bit more expensive, but none of my yard/garden tools require their carbs to be rebuilt every spring.

  20. I did the same! It doesn’t have to be choked, or warmed up. Runs smoothly from the first second. I still have the option to run it on gas. just the flick of a switch. Nice to have both options.

  21. I use E-85, but add sta-bil, carb/injector cleaner to all portable fuel containers, and haven’t had any trouble at all. The genset for emergency use needs to have a fuel shut off so you can run the carb dry after use. I keep my genset topped off with treated fuel and have never had a problem after six years and the genset is always ready and starts right up on my two month check.

  22. I stored 35 gallon food grade containers with ethanol-free gasoline and Stabil. Due to serious health problems I wasn’t able to use this fuel for years. I used the last of it in my lawn tractor after five years of storage with no problems whatsoever.

  23. I keep 5 gallon plastic containers to hold the normal E-10 gasoline for my generator and other small engine tools.
    I rotate by age and have been regularly using gasoline that has been stored for as many as 4 years with no ill effects seen on any of these tools.
    My “go to” solution?
    Pri-G. Dosed as per directions and then doubled, or tripled. Manufacturer states there will be no problems overdosing the gas.
    This stuff beats the heck out of Stabil.
    If I have a 5 gallon container that has reached my cutoff date, I use it in my personal vehicle. So far, no issues seen doing that. By me or my mechanic.
    Pri-G is a wonderful product. I recommend it.

    1. Pri-G and stabil operate differently… Stabil on fillup and Pri-G before use is best IMO… Pri-G restores volatility which is why you need to use every 6 months or so per instructions whereas stabil keeps water from condensating w/ alcohol in the fuel causing separation…

  24. I plan to purchase a propane powered generator in the very near future. Propane is easier for me to store, I cannot store gasoline where I currently reside. Propane will also be used to power portable heaters, cooking, and lighting equipment that I have. So for me propane is the universal fuel.

  25. Propane power generators are most assuredly the way to go. The fuel never goes bad in to be stored in large quantities easily and safely. In an emergency propane can be acquired far easier than gasoline. Gas stations, grocery stores, hardware stores and even Walmart carry the portable exchange bottles for sale. Even better is to have a large on-site tanks that can be refilled on demand buy delivery trucks. During localized or Regional emergencies propane is far easier to get than gasoline. Having an on-site tank gives you large personalized storage that is also nearly impossible for someone to steal. Whereas 10 5-gallon gas cans can vanish in an instant.

    1. Above ground propane tanks are easily kaboomed… Otherwise, ideal. In ground propane are much more expensive and difficult to install… Concrete/gravel filled block wall around propane tank is a great step in the right direction…

  26. I stored about 100 gallons of non-ethanol 92 octane in 1999 and started using it in 2010 for the yard power equipment. I had added 4 ounces Marvel’s Mystery Oil for every 10 gallons of gasoline. I had some water settling in the bottom of the containers but the rest of the fuel acted and smelled fresh. This was my experience. Your results may vary. There may be better stabilizers/additives on on the market.

  27. To Steve S, Marvel mystery oil is great. It is a super top-cylinder lubricant. At the fire house we had a coupla’ old engines with “auto” Miracle Engine oil injector tanks on them. We filled the tanks whenever needed. I add the stuff to all the gas in my old engines. The engines were still going strong after 50 years. I can’t say the same for the sheet metal here in New England!

  28. Something that hasn’t been mentioned yet is the new Dual Fuel generators made by Champion. They claim to be able to run on either gasoline OR propane with no special adjustments or system enhancements. Available here in the Pacific Northwest at Tractor Supply for a reasonable cost. Perhaps this might be an option.

  29. After Echo denied a warranty claim for a scorched 2 stroke because I used regular gas, I only use premium for anything with less than 4 cylinders .
    Easy start and smooth running ever since on generators, 2 strokes and riding lawnmower ever since.

    1. I had the same thing happen. Burned up an Echo chainsaw. Scorching inside the cylinder clearly visible through the spark plug hole. “regular” gas, I think E15 (seasonal change) at that time. E10 didn’t seem to cause any problems, but putting the E15 in there, with the right amount of oil, burned it up. Got on a chainsaw forum and discussed it with the pro’s… That is what I learned. Well, that, and to buy a pro level saw for my usage.

      We have a gas station NOT at the marina here that has a nice pull through pump WAY behind the station, that people can pull their boats right up to on the trailer either before or after an outing. I always pull up without a boat, and fill up my “little cans”.

  30. In spite of all the |store it dry” advice I store my out of season small engines “wet”
    After some research I found that all the gasoline “conditioner” were basically acetone.
    Also that hard start were due to “gum” in the small passages of he carb. This gum was worse in E10 because the water let the gas evaporate while keeping t there while it dried.
    I also found that the alcohol in E10 was isopropyl (the same as Heet) which absorbs the water and makes it “thicker.” The acetone will also mix with the gas/water mix and “thins” it back to a no water condition.
    So, my multi month storage routine is:

    1) I use only “premium” gas in all my carbureted engines since it is locally alcohol (and thus water) free. That makes it ready to evaporate easier even in season. The engines just seem to run better.
    2) When getting ready to shut down I pour at least a cup of acetone into the gas tank and run the engine for 10 to 15 min to be sure the acetone mixed gas is in the carb.
    3) Shut down the engine but leave the fuel line to the carb open. This keeps the carb wet and avoids evaporation and the “gum” it leaves behind.
    4) Open the tank fill cap and cover the opening with a thin plastic sheet (bread bag) and recover the opening. This prevents the gas in the tank from evaporating through the make-up air vent in the cap.

    When it comes time to start I only have to remove the plastic from the tank fill opening, set the choke if needed, and pull the rope. I have always had a first pull start

  31. The current fuel blends mess up generators and lawnmowers and all kinds of small engines. what I do is add sta-bil to my gas and a small amount of 2 stroke oil.I also run my gen once a month and add a load onto it after a few minutes. I also use synthetic oil in the engine. I have heard of plenty of generators lastings hundreds of hours.If you have the money get a gen. that is water cooled.

  32. I run my expensive Honda every month for 15+ minutes plus use it at tailgates. Use premium gas with Sta-bil. I would love to know how it would deal with E-10, E-15 and E-85 but I don’t want to risk damaging my expensive backup power. I’ve found that if I store it in the garage in the winter when it’s cold it will not start. If I bring it into the house for a day to warm up, it starts right up.

    For emergencies I have six 5 gallon cans numbered 1-6. I use #1 in January and July in my vehicle then refill it with Premium + Sta-bil. #2 gets used in Feb & Aug, etc. so I have 10 days of 24/7 fuel (30 gallons) on hand. Word of concern. Some places have restrictions on the amount of fuel you can legally store.

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