I'm not sure what this is properly called, you know, the gas mixed with
oil that you use in things like chainsaws.
I'm wondering if it has a "shelf life". Is there a period of time,
after it's been mixed, that it's not really good to use any more?
I'm pretty sure the oil will remain good, but the gasoline will age.
Old gas will evaporate and leave a hardened "shellac"-like verneer on any
parts it was be in contact with. This "shellac" must be removed.
Also, "old" gas jes doesn't work as well as fresh gas. Gasoline older
than a couple months should be replaced, if it hasn't already
But you're wrong notbob . Gas that has had a stabilizer added and has been
kept tightly capped will keep for a year or more - depending on temperature
variations where it's stored . I just finished off the last of last summer's
stores , worked just fine in the generator and Rusty Tractor . The
chainsaw/weedeater gas is fresh as of about 3 weeks ago ... until then it
was also last summer's gas . One thing - all my gas for portable equipment
is non-ethanol , it's bad enough we have to burn that shit in our cars , I
will not abuse my small engines that way . Corn should be drunk , not burned
To be expected. Hell, I'm only 67.
Gas that has had a stabilizer added......
....is no longer gasoline! It's now gasoline plus stabilizer.
I'm so sick of hearing about how "ethanol fuel" ruins engines. It's
all a myth.
I ran it in both my vehicles, a Dodge w/ a 318CID V8 and a Honda
in-line 4 banger. They both ran better and longer with ethanol. It
improved the V8's pre-ignition probs and the Honda had 250K
trouble-free miles on it when I sold it and the engine was the only
thing still working perfectly.
The problem has been portable gas driven equipment (chain saws,
leaf-blowers, weed-eaters), which are jes plain cheaply made junk,
BTW, ethanol is still in most of today's fuel supplies. In Brazil,
the auto petrol is almost pure ethanol.
On Saturday, March 12, 2016 at 11:07:52 AM UTC-8, notbob wrote:
I have been running regular grade gas e10 in all my chainsaws since e10 was inflicted on us. I haven't had one problem and I have saws tha have eaten over a 100 cord. I will usually dump left over gas mix after a month but I did that also before e10
Had to have two stihl blowers carb replacement. I think I can buy gas near
me, but I have to walk down to the dock on river. Also seems a can get 100
octane avgas ? My huskvarna saw has been sitting with gas for 10 years.
Starts righ up.
I've got a couple of bikes sitting out in the driveway that haven't ran
since the end of October. When I put the batteries in, I expect they'll
start and run fine like they have every year. Sometimes I use StaBil,
sometimes not. The pickup is semi-retired, gets one the road once or
twice a year, and it will start too. I honestly can't remember the last
time I filled it up.
ymmv, but that's been my experience.
There's a small-engine repair shop near here, that has a sign on the
door telling people to try it with fresh gas first (by 'fresh' they mean
less than a month old). I keep gas for up to a year and haven't had any
trouble with it.
BTW, it's not wasted after a year. I put it in my truck.
It's not so much evaporation as oxidation - and both the oil and
gasoline will oxidize. It is much worse if moisture is present.
If you mix oil and etanol free gas, and put it in a tightly sealed
container in a cool location, it will last many months to a few years.
Mix ethanol gas with oil and put it into a vented plastic gas gan in
your garden shed in the summer, a few months is pushing things.
You jes put two completely different gasoline mixtures in two
completely different vessels/environments. One in plastic, one in ????.
One with ethanol (+stablizer?), one not. One "vented", one not. One
in "cool" location, one in ¿hot? Summer location. With all those
variables, how you settle on the problem being the ethanol is a
Ethanol is MORE of a problem in an unsealed container. (ethanol is
hygroscopic - it attracts water) Gasoline in a sealed container needs
to be kept cool or it will burst (high vabour pressure)
If you want a premix to lat, you keep it in a sealed can in cool
conditions, and to be really sure you don;t use ethanol(because it
could already have absorbed significant moisture).
If you want gas to go bad really quick, you use ethanol gas, keep it
in an unsealed container, and subject it to wildly changing
Nowhere did I mention stabilizer/
So - the issues that will cause gasoline to go bad are:
1- oxidation due to being in an open container
2- moisuture from condensation being in an open container with varying
3- ethanol in the gas attracting and absorbing moisture from the air
being in a vented container.
4- evaporation of the "light ends" from the fuel
The only one that is related to ethanol is the attracting and
absorbing water from the air..
Now comes the real fun. The amount of water the ethanol mixture can
hold in suspension varies with temperature, so when the temperature
fluctuates, and the gas cools with close to the limit of absorbed
water in the mix, the water and ethanol "phase separate" from the
gasoline, and drop out into the bottom of the tank or container.. The
water also has oxygen absorbed it it - which, along with the ethanol
(also an oxygenator) causes the fuel to oxydize, forming gum, and also
(if in a metal tank) causes corrosion in the tank or container.
If that water/ethanol drops out in the fload bowl of the carburetor,
that water and ethanol attack the brass parts of the carb - in
particular the jets, which get restricted of blocked with the
"greenies" from the oxidation of the copper that is electrolitically
stripped from the brass - making the engine difficult or impsiible to
start - and making it run poorly if and when it does start.
The lack of "light ends" in the fuel makes it harfer to light and
reduces the octane as well as many other desireable properties of the
That is on a 4 stroke engine.
On a 2 stroke another problem rears it's ugly head. The fuel mixture
runs through the crankcase to lubricate the 2 stroke engine - and when
water is drawn into the crankcase along with the oil/fuel premix (or
in place of it if the separated water/ethanol is drawn from the bottom
of the tank) the engine parts are not properly lubricated, and the
moisture causes corrosion of the engine bearings, frank, and other
internal parts. Reduced octane due to evaporative losses is worse on a
2 stroke because the addition of oil to the mix has already
significantly reduced the octane of the fuel
Ethanol free gas does not attract as much moisture, and does not drop
that moisture out of suspension in such large quantities, so is much
less likely to cause any of the above-mentioned problems - and when
stored in a sealed container will last significantly longer.
SO - the ideal storage situation is ethanol free mix in a sealed
container stored in a constant low temperature situation/
The WORST situation is ethanol gas stored in an open container under
fluctuating (and generally higher) temperature conditions.
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