I almost didn’t get the Stationary Engine List done this
month, thanks to two weeks of horrendous computer problems. When I
finally got back on-line and downloaded all the mail there was such
a suitable-looking thread that I abandoned my backup restorations
and got to work! A contributor from Canada, for whom thoughts of
winter come early, began this thread, and the replies reflected, to
a certain extent, the geographical variety of contributors.
I was wondering what the general opinion is on draining fuel
tanks for the winter on gas engines. 1 have always done it, then
started out in the spring with fresh gas, but some people tell me
they don’t bother. Thoughts?
In my opinion, nothing serious will happen if you let untreated
gasoline sit over the winter. I have, however, encountered some
difficulty with engines stored for a few years.
I’m not sure about modern gas, but a few years back I had to
get a motorcycle going that had been in storage about five years.
The shutoff valve leaked fuel into the carbs, where it evaporated.
The resultant varnish built up to 3/16-inch thick in some places. I
came close to having to throw both carbs into the trash pile.
I’ve also seen engines where dried varnish completely
plugged up the gasoline lines, check valves, etc. Of course, they
had been stored for years. Bottom line: Over the winter, don’t
worry about it. Long-term, drain.
One argument in favor of draining is that next season you may
favor other engines in your collection, and this one might not make
it out to play. Then it moves farther back in the shed and misses
another season. Pretty soon it’s five years later and the tank
is filled with stinky goo.
We just bought a home in Florida that came with a riding mower
that hadn’t been run in over two years. The original gas was
still in it and the gas can was about 3/4 full and uncapped. I
fully expected to have fuel system problems, but it started right
up and ran fine. After mowing the yard twice it ran out of gas, so
I poured the two-year-old contents of the gas can into it and
finished mowing. No problems.
I guess that when I put fresh gas into it, it will decide (a la
Murphy’s Law) to make life miserable! That’s not to say I
advocate long-term storage without draining the gas – I seem to
have been lucky in this case.
I’ve never bothered, and so far haven’t encountered a
problem. Little two-stroke engines in things like weed-eaters and
chain-saws have started right up after as much as 10 years of
sitting, just by adding fresh fuel. I did find a Briggs &
Stratton a bit cranky on the first tank of gas, which had
evaporated down to maybe 30 percent of its volume – very sour
stuff. I just topped it with fresh gas, primed it with a splash of
fresh gas in the carb, and it was fine.
Two-cycle engines, especially ones running rich oil mixes, can
be a problem to start after a lay up. The fuel evaporates and
leaves the heavier stuff, which is not very volatile, making for
I’ve never had a problem from not draining fuel tanks over
the winter. However, I have encountered a stale smell in the gas if
an engine sits for two or more years.
I would be more concerned with the fuel bowls on carburetors of
small engines and lawnmowers. You should drain the tank, then run
the engine until it is out of fuel.
Over the years, I’ve dealt with too many springtime hard
starters. The gas can I use for outdoor power equipment never gets
filled without putting Sta-Bil in it first. That’s the same gas
can that I use to fill my old engines, and I use gas from it to mix
all my two-cycle gas. 1 don’t drain anything, I fill the tanks
up for the winter.
The last time I needed my generator it had been sitting in my
open garage for almost two years. It started first pull. I use
Sta-Bil on all my mowers, tillers, chippers and the like, and 1 can
go out in the spring and everything starts up like I used it last
Sta-Bil works really well as long as you fill your tank
I don’t drain the fuel tanks, but as autumn approaches I
start treating my gas with Sta-Bil. It doesn’t cost a lot, and
I don’t face spring with tanks, carbs, mixer, etc., full of
gum. The last time I forgot to use it, it cost me $75 for a totally
wrecked chainsaw carburetor, tank and engine. No trouble
The following comment is from Australia, where engine
show season lasts all year round!
I make sure the petrol engines are empty if they are going to
sit for a while, even if it is only going to be for a few weeks.
Modern unleaded fuels seem to go ‘off’ pretty quick, and 1
will not even think of putting LRP (lead replacement petrol) in any
of my engines. It goes off quick and fouls spark plugs like crazy.
My 12 HP Root & Vandervoort will not even fire unless I put
fresh fuel in it, and I know of a few other people with igniter
engines who have found the same thing.
I don’t see how you guys (and gals) can cope with having to
put your toys away for a few months every year! I would go stir
crazy if I had to go for more than a week without running an engine
and more than a month without going to a good engine display.
If you think you have a problem with fuel gumming up, go buy
some racing fuel and put it in your tank – it will clean up any
varnish. I used it by mistake once in a crawler that had been
sitting for a time. There was no regular gas around, so I grabbed
the fuel for the race truck and thought, ‘what the heck,’
and used it. It ran really rough at first and then started leveling
out. Took the carb off just to look and it cleaned up on its
On the subject of sour gas, has anyone noticed that two-cycle
gas mix does not seem to go bad as fast as straight gasoline? I
usually mix up a two gallon batch of 32:1 for the weed-eater about
once a year. Never seems to go bad, even at the end when I empty
the can. Is it possible that the two-cycle oil acts as a fuel
preservative? I have used this mix in the Hercules and am
considering going to it on all the engines because of its
long-lasting qualities. Seems the top cylinder lubrication of the
mix would be useful, too. Any comments?
I’ve thought the same. I think two-stroke oil helps to keep
the gum from solidifying as the gas evaporates. Makes a sort of
grease instead. Lots of people can tell you it doesn’t always
work, of course.
With luck, this article will reach the GEM readership before all
your preparations for winter storage are complete. Of course,
don’t forget to drain your water hopper – freeze cracks are a
lot more difficult to repair than cleaning stale fuel from a
Engine enthusiast Helen French lives in Leicester, England.
Contact her via e-mail at: Helen @ insulate.co.uk You can join the
Stationary Engine List on the Internet at: www.atis.net