best choices for fuel stabilizer for a generator

Fuel Stabilizer For Generator Use

A fuel stabilizer for generator use. It’s one of the best things you can do. With it comes peace of mind that your generator should start right up after having set idle for periods of time (in between occasional running to be sure it still works).

Here’s some of my experience and tips using fuel stabilizer for a generator, or any other motorized utility such as a snowblower, lawn mower, boats, etc.. Things which may sit around unused for a time (e.g. over winter) with gasoline in the tank (and/or carburetor).

I also have two recommendations. Both good choices. One, I believe, perhaps a bit better.


“The neglect of stored fuel is one of the weakest links in disaster preparedness. It is estimated that more than one half of the power generator failures that occur in emergencies can be directly attributed to fuel degradation.”

Power Research Inc. (PRI-G)

Not only might you have your own generator for use during a power outage, there are tens of thousands of generators at the ready in a wide variety of settings. This includes places such as hospitals, airports, cell phone sites, internet service providers, fire and police stations, large apartment buildings, office buildings, data & telecommunication centers, drinking water pumping stations, nuclear power plants, and many more…

The problem is, most generators just sit there unused for much of their life. And if there’s fuel in them, eventually it’s going to go bad! The question is, how long, and what can you do about it..

When you need it the most, your generator might not start – because you didn’t treat the gas with any fuel stabilizer additive. And eventually the old gas gummed up the works.. What you need is something like this:

PRI-G for 2 and 4 Stroke Engines

PRI-G fuel stabilizer is good for a generator

The weakest link in these generators is the fuel which often sits unused or not rotated for long periods of time. Even when running your generator a few times a year, the gas keeps getting older.

The problem is, the generator may become ‘gummed up’ or won’t run due to old fuel sitting in the tank, lines, fuel filter, carburetor, and even your fuel cans. Many of these perfectly good generators will fail when they are needed most – because of old fuel.

It is said that most fuel will maintain optimum freshness for ~ 3 months in good storage conditions. Most gasoline will continue to perform in the engine well afterwards, however, it does degrade over time.

Unfortunately, this relatively short ‘optimum’ shelf life can be bad for backup generators.

There is a solution to this problem however:


Fuel treatment with fuel stability additives.

There are many fuel additive treatments to choose from, and they are available at automotive stores, hardware stores, etc..

Many of them are formulated to keep fuel fresh for up to 1 year. Others, even longer.

PRI-G Fuel Stabilizer

Having researched this issue, I have come to the conclusion that PRI-G fuel additive is apparently better than the rest (though I’m not knocking the others which are fine too). While PRI-G costs a bit more than the others, it will treat fuel for years without issue.

The company is called Power Research Inc., and they make a product line under the name PRI-Products. Here’s their fuel stabilizer (gas or diesel) at their site on amzn..

( PRI-G ) Gasoline Fuel Additive
( PRI-D ) Diesel Fuel Additive

I believe it’s worth the extra few bucks than some competitors. Why? Because a generator can be a pricey investment. You want to protect it, and you want it to reliably start up when you need it most.

The PRI-G fuel additive listed above (16 ounces) will treat 256 gallons of gasoline. At the time of this update, the approximate cost per gallon to treat gasoline with PRI-G is only 11 cents. That’s no big deal to protect a generator.

Also, treat the fuel in your gas cans for assured shelf life longevity.

How much PRI-G (super concentrated formula) to treat 5 gallons of gasoline?

Squeeze an amount of PRI-G just above the 1/4 ounce line into the built-in measuring dispenser to treat 5 gallons. Technically, 0.3 ounces.

PRI-G will restore old fuel

“PRI can bring back to life most gasoline and diesel fuels of the worst condition. PRI has been independent laboratory tested on 10-13 year old fuels, and has restored the fuel to usable condition.”

The Shelf Life of PRI fuel stabilizer

PRI has an indefinite shelf life when sealed. It should be used within 3 years once it is opened. Store in a cool place out of direct sunlight.

Ken adds: I had not thought about the difference in shelf life for fuel stabilizer AFTER it has been opened. It’s important to keep in mind. You may have some fuel stabilizer (PRI or even STA-BIL) that has been sitting around opened for many years. You might want to consider replacing it..

“We have used this fuel stabilizer product for years in gas tank fillups for all of our shed power toys and lawn tractor. We live in New England, so our tools are stored for the winter, including the gasoline inside of them. Come spring, we have never encountered any problems with gummed-up carburetors or gas-lines since starting to use this product.”

~ one of many positive reviewers on amzn


If you look for fuel treatment at your local stores, there’s one brand often seen:

STA-BIL fuel stabilizer for a generator


I have used STA-BIL fuel stabilizer myself for some time (with no problems).. Although I have usually rotated or used my fuel storage well before one year.

I will relay a story for this update. I was recently given a snowblower that had been sitting unused for approximately 3 years. The fuel had originally been treated with STA-BIL. And there was fuel in the carb too. Anyway, I was surprised when that snoblower started up on the very first pull!

The Shelf Life of STA-BIL

The shelf life of all STA-BIL is 2 years after the bottle has been opened, provided it has been tightly capped and stored in a cool, dry place.

If you have a portable generator, take care of it!

– Use treated fuel to avoid gummed up carburetor, fuel lines
– Optionally drain the fuel from generator tank
– Switch off fuel line valve to run the generator ‘dry’
– Start it up at least once every several months
– Check the oil!

[ Read:

Best Extension Cord For Your Generator

Sea Foam Motor Treatment

Generator Maintenance

Generator Safety


  1. Good reminder and GREAT advertisement for PRI-G HAHAHAHA Will admit I use PRI products.

    I want to first start by saying the BEST fuel stabilizer is Propane, It doesn’t need any…. Get a Propane Gen-Set and a few 100# bottles and your good to go. Also get an adapter hose that will fit your 500-1000 gallon tank if your on Propane.

    BUT, this is about fuel stabilizers.

    I agree on the PRI products, but here are a few other ideas that come from my Chemistry buddy, Doc.

    Store only Premium Gas and/or non-ethanol gas. Regular gas with 10% ethanol is, in his words, “CRAP!!!”

    Please remember ethanol WILL eat the rubber lines and rubber parts.

    If you want to add a treatment to the Premium and N-E fuel, it will last for well over a year.

    Also store the Gen-Set with no fuel in it, run it completely empty, open the fuel tank (outside) and let if completely dry-out.

    As far as the fuel you store, why not fill the Car/Truck once a month with the stored Gas? And refill the cans with fresh fuel? Even if you have several, if you rotate this way you’ll probably change out the fuel a couple times a year.

    As an added item, we just had a discussion on another article on treating Kerosene. If needed or not. I believe the consensus would be to go ahead and treat it with PRI-D since it actually is classified as #1 Diesel, it does have a slight more waxes in it, but minimally.

    1. Probably a dumb question, but anybody know if it’s normal for the fuel treated with Stabil to lose a little of it’s efficiency in the MPG’s for vehicles? I seem to notice it does and I rotate my fuel out every 3-4 months.

      1. – Silver Lodge –
        Sorry, didn’t reply the other day because I don’t “know” for certain. What research I have done on the subject suggests that even though treated, Sta-Bil still allows some loss of some of the lighter components (Butane, etc.) from stored gas. While it is still usable, you can have some loss of power. PRI-G supposedly reduces this loss, and can replace some of the lost components by adding more. (Sta-Bil doesn’t work that way). I haven’t tried it, but supposedly you can add PRI-G even to old gas and rejuvenate it. (I wouldn’t like to mix additives, though.) That’s one of the reasons I went to PRI-G.

        – Papa S.

        1. depending on your location- Gas sold is oxygenated in the winter months , this lowers fuel efficiency also.

  2. IMO the first and best place to start is to use fuel without ethanol. An increasing number of places are selling ethanol free gas, albeit at a slight premium over the ethanol diluted stuff. Just google it to find a station near you.

    Then, I add Sea Foam. Available in lots of places, it is not only a stabilizer but it also cleans out carbon and “koodies” in internal combustion engines. Its been around since WWII, and works! Perhaps Ken can post a link to the item in his Amazon store?

    [ Ken adds: Here it is… Sea Foam ]

    1. Thanks for mentioning the recommended use of non-ethanol gasoline!

      I only use non-ethanol gas in ALL of my gasoline powered engines, including generators. Fortunately there is a gas station less than 10 miles from here that sells it.

    2. Lucas fuel additive is another you can use just like sea foam. Both are available at any auto parts store

    3. How long does SeaFoam store for? have an opportunity to get a few cans, inexpensively.

      1. grannyo I checked the SeaFoam website and in their FAQ it says a unopened can of SeaFoam has no expiration date. And an open SeaFoam container they commented they would not be worried to use it for years unless contaminated.

  3. PRI-D in the 125 gallon bed tank in the pickup and Power Service in the main tank and for travel. PRI-G for the car extra fuel and gas tool’s tank. Biggest thing is to buy only clean gas, no alcohol or BS gas station additive in it. In the winter the truck and tractor get anti gelling agent. The whole house generator runs on L.P. so it’s just keep the tanks topped off. Also have a small out building that we use for flammable liquid and materials. And yes I do have all the MSDS sheets in the office on everything in shop and out building storage. When winter comes run all the gas tools dry so no fuel is even in the carb.

  4. I store around 80 gal of gasoline (10×5 gal plastic containers + a 30 gal elevated tank for gravity feed into equipment). My demand for gasoline varies by season so my rotation slows significantly in winter months. I use both Stabil and Sea Foam and have had no problems with gas going bad.

    Sea Foam has been around since the 1920’s I’ve been told, and was touted for keeping 2 cycle marine engines from gumming up. Starting a few years ago it began being touted as a fuel stabilizer/life extender. I’ve used it in gasoline stored for over a year and it seems to work. I’ve used it in a couple of small engines showing signs of carburetor gumming and experienced much improved performance after running a tankful of Sea Foam treated gas. It smells suspiciously like isopropyl alcohol, but seems to work as advertised.

    Most folks know this, but I’ll mention it anyway. After running your generator, shut your gas off at the tank and allow the carburetor to run dry to stop the engine if you are not going to use it for a while. Run the generator occasionally for a few minutes every month to keep internals lubricated and keep gaskets from drying out and again let the carburetor run dry to kill the engine.

    If your generator is electric start, put a battery maintainer on the battery. The idle battery can slowly loose it’s charge. A discharged battery exposed to sub freezing temperatures is subject to freezing and failure.

    1. Dennis, re: generator battery, yup. Just got a new battery, the original was two years old and would not hold a charge. I was not diligent last winter cranking the generator every month. So, new battery, beats hand pulling a 21 horse power engine. I do have compact power packs for jump starting if needed. Lax on preventative work, always ends up forking over some dough.

      1. Grey,

        Yep, big difference hand cranking a 3 hp lawnmower and a 21 hp generator (mine is just 15 hp, but still). Had to replace my battery last year. It’s one of those specialty odd shaped flat gel-cell batteries mounted where nothing else would fit.. After I priced a new one, I bought a $29 Wally World lawn tractor battery (1/4 the price), relocated the battery by building a battery box and extending the cables. 50% more cranking amps and a heck of a lot easier to service in it’s new location.

  5. List of Ethanol-free gas stations in the U.S. and Canada

    1. – scprepper –
      Per PRI website, current record-holder is 12 Years and counting. Don’t think I want to try for that record, but it seems at least twice as reliable as Sta-Bil product. I have quit buying Sta-Bil at all. PRI-G is a little bit pricey but I have been pleased with results (No problems apparent) at up to 2 years.
      – Papa S.

  6. Kind of a moot point for us at the moment as we cannot afford a generator right now, but my wife and I have discussed this and since we’re out in the country and use propane for heating, we figure to go with a propane generator when we can, and have the propane company put in a bigger tank. The primary reason for this is fuel. Storage, availability, etc. It just seems to us that propane would probably be the better choice for our situation as if there is a prolonged power outage, a 500 gallon main tank will run the house and a generator for quite a while. This way we don’t have to worry about fuel availability, storage, “freshness”, etc. I know that in urban areas one can get a natural gas powered generator for the same reasons.

    1. Restoring Brad,
      I am thinking along the same lines. Add to your list of pluses (+), generators that run on natural gas or propane tend to wear very slowly, so they last a very long time.

      1. Will a diesel need an ignition system to run on propane or does it auto ignite?

      2. We have a natural gas standby, just make sure you do regular maintenance like check/change the oil, filter and plug on it. Ours is about 4 years old and with regular maintenance we’ve been told it should last a good 15-20 years if not longer.
        It is set to run every Sunday for about 15 mins to circulate the oil keep the engine running . It turns on about 10 seconds after the power goes out, when it goes out. As long as the natural gas is running we won’t have a problem.When we were looking into a standby generator, we were thinking about doing diesel but we can’t have a pig for the fuel where we live.

    2. We have two 1000 gal. propane tanks below grade in a concrete vault on reinforced slab. Picked up the tanks for about the same price as a new 350 gal. tank as no one wants them. Picked up steel plates like they lay down on road repairs from a construction site. The prime contractor was freaking out on what to do with them after the job was completed. Told him I had a home for them as a blast cover over my propane tanks. It was a lot of work to size and install but the tanks are out of sight and bullet proof. You could ask why we went to all the bother? We run forced air heating, on demand water heaters, refrigerators, wall heaters in both master baths and two kitchen stoves. Pick up the whole house Onan generator off a commercial demo building site for next to nothing. Why I’m telling you this is there is all kinds of ways to afford what you need. I’m a pack rat as my wife tells it. She is not unhappy with her free chicken coop or little art studio that cost next to nothing. Put in the whole propane system at about .25¢ on the dollar. One man’s trash is another man’s treasure.

  7. Kits are available to convert gas gens to run on propane.
    That means it will run on either fuel.

  8. This may be a stupid question, but if you use PRI-G treated gas in the generator, do you still have to let the carburetor run dry? Why? I’m shopping for a generator and trying to learn as much as possible. Thanks.

    1. – Neighbor –
      I really don’t know about “have to”. I want my generator to start quickly and easily, even under adverse conditions. Why take the chance?

      – Papa S.

  9. I have had bad experiences with Ethanol gasoline causing “apple jelly” like gunk in my float bowls and galvanic corrosion in my small engines’ carburetors. Now I just use non-Ethanol gasoline in my carbureted engines (hard to find and more expensive in upstate NY) and run them dry in the winter. No more problems. Even with two year old gas, no additives. Added gas shut off valves to every carbureted engine and then run the float bowls dry. Then they start right up in spring, or whenever I want with the Snowblower….

  10. I store 75 gallons of gas all the time. Have been using Sta-bil with great success. Every spring in March the stored gas gets used in my truck and replaced with fresh gas. The bottle of Sta-bil in my hand says treats for up to 2 years, 1 ounce for every 2.5 gallons of gas. There are 5 generators of various sizes in my garage, the oldest being 36 years old and everyone of them run like new. Sta-bil has served me very well all these years even with 10% ethanol gas. I have also heard and read good things about Pri-G and what I’ve read it is probably a better product but since Sta-bil can be bought almost anywhere and has served me VERY WELL for over 36 years, I’ll continue to use it. The old saying, “if it ain’t broke, don’t fix it”, comes to mind here.

  11. As NRP said in the first post, unless you are storing an enormous amount of gas just ROTATE IT INTO YOUR VEHICLE once a month and save the cost of additives–Sheesh it’s easy and doesn’t cost anything. (KISS)

    As far as generators go, has a sportsman’s DUAL FUEL generator for only $249 I was going to buy a bigger gen but this size will run my fridge and a light/fan but what I realized is it uses far, far less gas per day than a bigger capacity unit and for the price you can’t beat it…

  12. How difficult is it to install the propane kit? Better question… I’ve got a dead champion that came dual fuel, anyone know where I can find out what all parts come in the kits? I’m not averse to cannibalizing the champion if it’s a cheaper solution. We’re only generator power, I’ve got panels, but the battery bank cost… Haven’t gotten there. I’m looking at a 4000 Onan genset, too. I just picked up a Coleman powermate maxa extended run 5k today with the Tecumseh 10 hp. It’s the one I’m thinking of converting. It’s more like a good old late 70’s Chevy compared to the crappy Dodge neon that falls apart and wasn’t made to last.

    1. John Taylor,
      Seafoam is a good product for cleaning.
      As far as a fuel stabilizing additive, I’m not so sure.
      I had fired up my two genies today. One in the camper…I keep forgetting about. I haven’t ran for a couple years. It took awhile to start it. Help of ether to start and it ran rough.
      I added seafoam and the idle smoothed out.
      Filled the tank with ethanol free fuel and let her idle.
      I use seafoam in all my small engines that sit, but I also add Stabil to any fuel that sits stored in cans.

      The gasoline of today is crap

  13. Rejuvenation of old fuel really got my attention. In a survival situation that would come in handy.

  14. I have been using Seafoam for years.
    My generator is stored with ethanol gas and seafoam, my 4 wheeler stays at hunt camp and may not be started/ran for months at a time.
    Never a problem with either.
    I have a couple full 5 gal cans in storage, ethanol gas.
    I like Seafoam

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