How Long Till Treated Fuel Really Goes Bad?

[Quadrasteer]

Have too many machines with large fuel tanks to have to completely empty them. Some of the Gens. like my Coleman Powermate 7500 vertical have large, not easily drained fuel tanks. All probably have non-top tier regular with Ethanol Shield and or MIB in them. I usually drain the carb and tank if possible but not really sure when the fuel absolutely needs to be removed (and maybe put in my lawn mowers). Thanks

 

[2strokeNorthstar]

A lot depends on the climate. I have gas that's over a year old and still works fine in my yard equipment.

 

[TazzySpazzy]

I have left regular non-treated ethanol infused pump gas in a generator outside for about 8 or 9 months and it still fired up no problem. Of course I shouldn't a dun it but it did work OK.

 

[zzyzzx]

https://www.goldeagle.com/product/sta-bil-fuel-stabilizer/

• Keeps fuel fresh for long term storage – up to 24 months

 

[Fordiesel69]

Ethanol free 1 year. Maybe 2. After that its a gamble.

Ethanol i can tell you 5-6 months and it still burns. I have not gone further to test.

 

[gfh77665]

Gas lasts longer that most people think. Of course after 1-2 years its not in prime condition, but if "will still burn and not blow the engine up" is what you are asking it might even go 3-4. Head space is what kills gas. Along with preemptively adding Stabil, top off any fuel tank literally to the rim before storage if you can. That does two things, 1) prevents condensation and 2) prevents VOC's (including octane) from flashing off.

If I had a half full tank, I would add 93 octane to fill up then run it almost empty. Next tank run a 2X dose of PEA cleaner (Techron) through. Of course if its been 10 years or something, do not crank at all. Find a way to drain.

 

[TazzySpazzy]

Draining the carb is probably more important than the tank. The ethanol blended gas just seems to destroy carbs or at least require serious cleaning. My local small engine repair shop sells both PRI-G abd Stabil but they recommend ethanol free fuel as much better than the additives. When winterizing my 2-strokes I always drain the tanks and then add a little ethanol free mix and run them dry.

You can always use a fluid transfer pump or siphon to drain tanks without a valve at the bottom.

 

[Quadrasteer]

So as it turned out, in the Generac GP700E (older version), I did drain the fuel before storage, which I usually don't do, but...I guess that since there's no side drain plug on the float bowl I must have ran it dry and still left a slight bit of fuel in the bowl. Now I starts fast but only runs on full choke. Half choke it runs but not well, here we go again, and it's not an easy carb to remove. Back to the fuel question...the machines that I'm concerned about have fuel that is at least 3 yrs. old in them. Some maybe as long as 5 or 6 yrs., that why I asked what is too old. I usually run them if I get a chance and if they run well I return them to storage. When you siphon the fuel out you usually leave the worst part at the bottom. Maybe I should do one at a time and use a water separating funnel to put it in my mowers.

 

[TazzySpazzy]

I have read that gasoline degrades relatively quickly in terms of losing octane as well as pulling in moisture due to the ethanol, so, personally speaking, I would only put 5-6 yr old gas in something inexpensive and expendable. I hate to waste anything but neither would I want to create a problem due to old gas. Just for instance, new gas powered tools from Stihl specify not only a max of 10% ethanol in the fuel but to not use fuel/oil mix older than 30 days. I have taken apart and cleaned a carb on a 14hp kohler that had ethanol pump gas sit in it for about 6 months and boy oh boy what a freakin' mess that was. Fortunately 4-stroke carbs seem to be much more forgiving than 2-stroke carbs.

 

[Quadrasteer]

I've only had an issue with old gas from storage in plastic cans or containers left out in the sun. I put some in an Ariens mower and it spit and farted so I added an MIB sock and some Isopropyl dry gas and it got better. I also usually add some fresh fuel with the old. My issue is that when you have many machines filled with fuel in large tanks, how often do you really need to replace it with fresh fuel? I guess it depends on how old and where the machine was stored. Many years ago I bought a 1951 Chevy Sedan Delivery from a farmer that left it out in a field for years. I towed it home and, I was younger then LOL, and put a batt in it and tried to start it. To my surprise it started, not well, it smoked and burped and spit but it ran...for a short time.

 

[Olds394]

The latest I’m reading about is non vented containers, like metal, being the most important.
My idea is to store gas outside the machine and strain the gas when filling up the tank.
It’ll either burn or it won’t, but any gel or varnish should be caught in the funnel. Gonna try Pri-G next. ???

 

[The motor guy]

Have too many machines with large fuel tanks to have to completely empty them. Some of the Gens. like my Coleman Powermate 7500 vertical have large, not easily drained fuel tanks. All probably have non-top tier regular with Ethanol Shield and or MIB in them. I usually drain the carb and tank if possible but not really sure when the fuel absolutely needs to be removed (and maybe put in my lawn mowers). Thanks

I have the same problem, been looking for a simple way to siphon fuel out that's safe and not take all day. Back in the day everything was carbureted and chewed through fuel with ease, now it's like you can run around all day on 2 or 3 gallons.