Gas tank empty or full during storage?

[bigdog]

I know it's still summer with lot's of good boating weather in front of us,
and hate to bring up the topic of winter., but............

What is the Forum's opinion about winter storage regarding boat's gas tank?
Gas tank empty or full during storage?
Have heard pros and cons?

Opinions appreciated.

[AC2717]

full to the brim
with valve tech or other treated gas
that way you have a full tank going into the next season with one less thing you have to pay for to get the summer place up and running after a long harsh winter

[chipj29]

I think this is one of those topics you will likely get 49% ppl saying fill it up, 49% saying empty it, and 2% don't have an opinion.

Personally I am in the keep it empty camp. Even if stabilized, it is possible that the fuel breaks down during the storage period. If it does break down, it is difficulty to siphon off a large amount of fuel and dispose of it.

When storing, I siphon off as much fuel as I can. Then I add 1 gallon of stabilized fuel to the tank. Once that is in there, I start up the motor and let it run until the stabilized fuel has made its way into the motor (you can tell when it runs a little rough).

When taking it out of storage, I fill the tank with nice fresh fuel (89 octane) and off I go.

FWIW, I have been doing this for my Sea Doo and both my snowmobiles for several years. I have not had any probs doing it this way.

[dippasan]

Two schools of thought on this since the introduction of ethanol in fuels. A full tank means the potential for more ethanol to absorb moisture and potentially a large amount of fuel that can go bad and to have to pump out or dispose of in the spring. ($$$) The other opinion is that an empty tank means condensation can form on the walls of the tank and contaminate the gas. I now just treat it at whatever level it's at with Star Tron enzyme treatment and Sta-bil. I have lots of motorized seasonal "things" (motorcycles, snowmobiles etc) and I have found that the Star Tron enzyme treatment is a must for storing fuel.

[dt5150]

i keep mine full to avoid as much condensation as possible. with stabil marine added of course.

[LIforrelaxin]

Well, I do this different the most probably, but I run fuel with Stabilizer all summer long... and then just put the boat away for the winter...

That way I know the stabilizer is distributed through the entire fuel system... and don't even have to think about....

I have been doing this for 8 years now, with no issues..

[SAMIAM]

I use Star Tron or Stabil Marine Formula for everything and have had no problems. A landscaper that I know told me a secret.......says he uses high test in all of his mowers and 2 cycle equipment and has never needed stabilizers. I'm wondering if anyone else has tried that.

[Diver Vince]

full tank with lots of Star Tron.. In fact never put gas into the boat without copious amounts of Star Tron in it.

[RLW]

I use Star Tron or Stabil Marine Formula for everything and have had no problems. A landscaper that I know told me a secret.......says he uses high test in all of his mowers and 2 cycle equipment and has never needed stabilizers. I'm wondering if anyone else has tried that.

Before I did that I would double check the octane suggested by the manufacture as many engines will not handle a continue use of the high octane. Lawn mowers is one that it is not recommended to be used in.:)

[upthesaukee]

when I got my new boat two summers ago, I asked via email how Mercury felt about storage over the winter. They told me to fill the tank with treated gas, ie: Stabil, Startron, Valvtek, etc. Rationale was that with a tank that is not full, condensation can form more easily in that environment.

JMHO, which normally means Just My Humble Opinion, but in this case is not only mine, but Just Mercury's Humble Opinion. :D

[trfour]

when I got my new boat two summers ago, I asked via email how Mercury felt about storage over the winter. They told me to fill the tank with treated gas, ie: Stabil, Startron, Valvtek, etc. Rationale was that with a tank that is not full, condensation can form more easily in that environment.

JMHO, which normally means Just My Humble Opinion, but in this case is not only mine, but Just Mercury's Humble Opinion. :D

Mine too Uppy...

The reasoning behind topping off your fuel and or gas tank is that there is a temperature drop over night and it doesn't take that much to facilitate condensation build up on the fuel tank walls, If said tank is not full.... I hope that's enough PERIODS. It be like a rain forest in your tank without being FULL.

I've been a heavy truck, construction equipment and diesel mechanic, high performance boats and automobiles most of my life, I started in 1950. I've been personally responsible for many Large Fleets of trucks to start in the winter mornings and they were always topped off with fuel before parked for the overnight. At 'ANY' long period of storage, the fuel tanks had to be topped off as well.

I stored the boat at the camp on Paugus Bay, most every winter, with a full tank of fuel and never once, did I have a problem with condensation building up and contaminating the fuel, and or gas... When the boat needed any refurbishing, outdrive or tune up over the winter I would take it down to my Brother's for storage as he had a heated garage where I could do the work when needed.

Terry
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[DBreskin]

Condensation occurs when relatively warm, moist air meets a cold surface.

My fuel tank is below deck with insulating foam around it and the carpeted cockpit sole above it; it's pretty well insulated against rapid temperature change. I've stored my boat over winter with a full tank, a half-full tank and a nearly empty tank and never had a problem with water in my fuel.

If my tank is cold and the outside air is warm, my tank will warm up and as it does any air in the tank will expand and vent to the atmosphere. If my tank is warm and the outside air is cold, my tank will cool and draw in air but since the tank is warmer than the air it is unlikely to result in condensation.

Maybe I'm just lucky, but I suspect fuel tank condensation is more of a problem for those with tanks that have outside walls exposed to the environment; especially hand-carried outboard engine tanks (which are easy to empty for the winter).

[MAXUM]

Everything I have ever heard and read suggests that full tanks with treated gas is the way to go. That's what I've always done and I've never had problems. However it's not just treating what's in the tank, running the engine long enough to get that treated gas into the entire system is essential.

[dippasan]

Everything I have ever heard and read suggests that full tanks with treated gas is the way to go. That's what I've always done and I've never had problems. However it's not just treating what's in the tank, running the engine long enough to get that treated gas into the entire system is essential.

You are absolutely correct! Shutting down the engine and then treating the fuel in your tank does nothing for what's in the fuel lines, pump, carbs etc. The treated fuel must be run through the entire system before storage.

[dt5150]

every drop of gas that goes in my boat is treated with marine formula stabil, irregardless of the time of year. i usually only fill it twice per season anyway.. :laugh: