The Boating Forum - winter storage..gas tanks full or empty

I get mixed opinions on whether fuel tanks should be full or empty for winter storage. All opinions would be appreciated.

Keith

you will problably still get mixed opinions. I have always heard full to prevent condensation but I have never done it. I hate the thought of the gas sitting in the boat all winter and not being fresh when the season starts, even with adding stabil.

I have twin 150 yams and add ring free and startron stabilizer to fuel when I fill up. Went fishing yesterday and main tank is just about empty....still have 80

I vote for full. Gas is designed to have a shelf life of 12 months. I quit using stabilizer years ago.

Snowwolfe - 9/9/2006 2:16 PM

I vote for full. Gas is designed to have a shelf life of 12 months.

I think that WAS true for MTBE additives, but not for ethanol. I think it drops by one octane rating per month now.

I have twin 150 yams and add ring free and startron stabilizer to fuel when I fill up. Went fishing yesterday and main tank is just about empty....still have 80+ in auxilliary tank and will be laying the boat up before using up the auxilliary. Thanks for the reply.

Keith

Here's one, half tank treated or not, do not plug vent, fill with some fresh gas start of season, run out any fogging oils, check plugs change if necessary.

What purpose served with half tank????? If ethanol attracts condensation as I have been told it does then it would seem to me that empty is the way to go and start fresh in the spring with treated gas. What harm, if any, is low to empty tanks for winter?????? Does an empty tank invite condensation???????

There is no real reason for it other than not having a empty tank of fumes nor a full tank to go sour, kinda of in the middle and it works.

As for condensation and water collection, in even a empty tank, conditions aren't right for major amounts to accumulate. The tank is vented and ambient temeratures changes don't heat and cool fast enough to promote condensation through winter lay-up.

drain the tank to be on the safeside. you dont want to spend next spring on the sidelines

For years I kept tanks full until on one of my boats the heat of the sun cause the tank to puke out of the overflow and took off the boat name.

After that a mechanic told me either keep them full or empty. If empty you'll not get condensation.

So now the boats and cars stay empty during winter storage.

Jeff

savage - 9/9/2006 8:19 PM

Snowwolfe - 9/9/2006 2:16 PM

I vote for full. Gas is designed to have a shelf life of 12 months.

I think that WAS true for MTBE additives, but not for ethanol. I think it drops by one octane rating per month now.

The ethanol only accounts for 2.5 % of the octane rating so that would end at about 2.2 for 89 octane.

I am still going to fill the tank before I put the boat up and run Stabil.

Just one man's POV...

keith1313 - 9/9/2006 8:52 PM

What purpose served with half tank????? If ethanol attracts condensation as I have been told it does then it would seem to me that empty is the way to go and start fresh in the spring with treated gas. What harm, if any, is low to empty tanks for winter?????? Does an empty tank invite condensation???????

Since an empty tank contains air, air contains water vapor and the tank can vent a bit over the course of the Winter -- particularly in the Spring when there is a relatively large temperature range over the course of a day -- yes, an empty tank invites condensation...

TED

How long is layup ? 4 months I fiq gas will last at least that long I VOTE FOR FULL

savage - 9/9/2006 3:19 PM

Snowwolfe - 9/9/2006 2:16 PM

I vote for full. Gas is designed to have a shelf life of 12 months.

I think that WAS true for MTBE additives, but not for ethanol. I think it drops by one octane rating per month now.
People used to say that was true for non oxygenated fuel, but now with mtbe it's no longer true. Who knows. I add stabil and leave it close to full every year, with the exception of last year. Last year I knew we would be switching over to e10, so I wanted to run out all of the old stuff before filling up with fresh new e10 in May. I think the full tank idea has been more popular up north, but now with ethanol who knows.

jobowker - 9/10/2006 11:23 PM

savage - 9/9/2006 3:19 PM

Snowwolfe - 9/9/2006 2:16 PM

I vote for full. Gas is designed to have a shelf life of 12 months.

I think that WAS true for MTBE additives, but not for ethanol. I think it drops by one octane rating per month now.
People used to say that was true for non oxygenated fuel, but now with mtbe it's no longer true. Who knows. I add stabil and leave it close to full every year, with the exception of last year. Last year I knew we would be switching over to e10, so I wanted to run out all of the old stuff before filling up with fresh new e10 in May. I think the full tank idea has been more popular up north, but now with ethanol who knows.



Man its great to live in the south :grin: Hope yall ,ooops I mean 'you guys' fiqure this out soon :tht_rulez:

I live among several petroleum engineers and I reasked the question. There answer is the same. Gas has a 12 month shelf life before it begins to lose octane or begins to break down.

I don't have a clue. I have been doing it for 20 years. Full tank with stabilizer. Never had a problem, never will !!!!!!!!!!

Tedj101 - 9/9/2006 7:56 PM

keith1313 - 9/9/2006 8:52 PM

What purpose served with half tank????? If ethanol attracts condensation as I have been told it does then it would seem to me that empty is the way to go and start fresh in the spring with treated gas. What harm, if any, is low to empty tanks for winter?????? Does an empty tank invite condensation???????

Since an empty tank contains air, air contains water vapor and the tank can vent a bit over the course of the Winter -- particularly in the Spring when there is a relatively large temperature range over the course of a day -- yes, an empty tank invites condensation...

TED

Sorry Ted... Disagree. The reason the tanks that are less than full (or completely empty) is the fuel itself does not change temperature with its surroundings (the boat) at the same rate. It's the fuel itself expanding and contracting that creates the condensation. Either full (less room for air) or empty (no fuel epanding/contracting to suck air in).. I personally have just run stabilizer for the last few months and try to get it as low as possible before storing. I also like the fresh fuel in the spring reasoning as well.

What's winter storage?

Theory 1: Empty tanks will fill with water over the winter due to condesation
Theory 2: There wil be no meaningful accumulation of water in an empty tank - possibly because of the dry winter air and the lack of flow through circulation
Experiment: Store empty each winter for 15 years along with a handful of friends and monitor the results in the spring.
Result: No water in the tank - ever.

OTOH, everyone that I know that has had a fuel problem with either water or MBTE/E10 mix has stored their tanks full. No one that stored empty has had any problems.

jeffgrice - 9/9/2006 5:31 PM

If empty you'll not get condensation.


I've always understood it to be just the the opposite. If the tanks are empty, there will always be air flowing into and out of the tanks because of thermal and barometric expansion and contraction of the air. If warm moist air goes in, and then the termperature drops (as it would at night, most every night), water vapor is going to condense out on the sides of the tank and then stay in the tank. Over time and many heat/cold cycles of condensation, this can cause quite a buildup of condensate. (Think of an empty tank as a "dew collector.") If your tanks are full this won't happen anywhere near as fast because there's hardly any room in the tanks for air in the first place.

Edit: There is going to be temperature change whether or not there is fuel in the tank. Yes, a full tank of fuel means more "thermal mass" (bigger heat sink) but it also means there won't be much room in the tank for air, as stated above. If there's no room for moist air to get into the tank, then deposit its dew, then come back out of the vent as drier air when the day warms the air back up, then you're just not going to get anywhere near as much condensation.

All other things being equal, 100 gallons of air at 60% relative humidity contains 100 TIMES as much water, by mass, as ONE gallon of air at 60% relative humidity.

How about leaving the tank empty and plugging the vent?

I spent 2-3 hours online researching what to do about storing gasoline over the winter at most name brand fuel websites, as well as Honda, Merc, and Yamaha's websites. All say gasoline stored should last about a year, even without adding any stabilizer. Written recommendations online was to store empty (totally empty/drained) or full if impracticable to totally empty. I also spoke to three mechanics who advised me to add stabilizer. I have a new boat and motor and the Merc mechanics told me I didn't need to use StarTron because everything was new.

I have an aluminum fuel tank and do not want any oxidation to start by storing my tank empty. I plan on using Sta-bil and that's it! I had used Sta-bil on some MBTE gas and stored it for two seasons. My old boat ran fine and started great on two year old treated gasoline.

Howard

My Merc dealer said to use up the fuel (still from last year) and do not top off for the Winter. I read somewhere that there's a bill floating around the Maryland legistaure that would permit non-ethanol gas for marine use. Maybe in time for the Spring 2007??

"All other things being equal, 100 gallons of air at 60% relative humidity contains 100 TIMES as much water, by mass, as ONE gallon of air at 60% relative humidity."

That might be true, but the fact is, you have very little transfer of air in and out of your tank. It's already full of air/fumes - there's little impetus for air transfer even with rapid outside temperature changes.

I've always stored with about 1/4 tank, sometimes a little more. In the spring I fill up, run the boat for an hour, change the fuel filter and get 1 or 2 tablespoons of water (for the whole previous season.) And I'd bet that even that is not the product of condensation.

This year I expect nothing, because that little bit of water will be absorbed by the e10.

Boat lays up generally from late November to late March. I add appropriate amount of stabil to whatever fuel remains in tank in late November and add fresh fuel when I use boat for first time for the season in late March.

jeffgrice - 9/9/2006 6:31 PM

For years I kept tanks full until on one of my boats the heat of the sun cause the tank to puke out of the overflow and took off the boat name.

After that a mechanic told me either keep them full or empty. If empty you'll not get condensation.

So now the boats and cars stay empty during winter storage.

Jeff





same thing happed to me, except it removed some stripes and bottom paint. that was the last time i left the tank topped off and that was 13 years ago, and i have had no fuel problems in the spring.

Lay up... not here.. winter are good tuna and wahoo months.... :)

I work for an oil company and deal with tanks every day. Keep tank full - use Sta-bil and you will not have issues. Trying to completely drain the tank dry is a hassle plus your seals and fuel lines can dry up and promote cracking and leaks. Only hassle with this is the $$$ for the full tank of gas!

toothferry - 9/11/2006 10:00 PM

I work for an oil company and deal with tanks every day. Keep tank full - use Sta-bil and you will not have issues. Trying to completely drain the tank dry is a hassle plus your seals and fuel lines can dry up and promote cracking and leaks. Only hassle with this is the $$$ for the full tank of gas!

Thanks for the reply. If sta-bil is the answer...Why does it matter whether tanks are empty or full? It seems to me that just adding sta-bil should be enough? By the way each tank of gas was treated with ring free and startron. Further opinion would be appreciated.

Keith ;? :thumbsup:

I would taunt you poor sob's up north about winter storage but then you might want to move to Florida. ;)

Hi Guys this is my 1st post on this forum after reading for months. I Work for a Marina/Dealership in north east Mass. I work in the service department as a writer consultant, mechanic and rigger. It was my responsibility to research the answer to this question so I contacted our BRP, Yamaha, Merc and Volvo reps to find their recommendations. The 1 thing they all had to say in common was that your tank should be empty. The E-10 will draw moisture from the air and with the fuel systems being open systems the opportunity for this to happen is great. The train of thought being you're going to get condensation in your tank no matter what you do. This being said it's easier to deal with a bit of water in an empty tank then a bit of water in your fuel. Both scenarios require the evacuation of the water by mechanical or chemical means, both of which will be easier with an empty tank. I have no personal experience to speak of in terms of E-10 enriched fuel as this is the 1st season for me and my Whaler with the "improved" fuel, however I though I'd share the results of my research with you.

I store mine nearly empty, never had a problem. I think a lot of the myth of condensation problems comes from aircraft experience and old boats. A light airplane often has the tanks built into the aluminum wings. Leave an airplane stored outside on a clear night and those wings will radiate heat and be very cold in the morning. The wings will have dew all over, and if the tanks are empty you can expect to have condensation in the tanks too ... and lots of it. Thats because the tanks are made of a heat conducting material and are exposed to the clear sky overnight. Some old boats also had exposed metal tanks.

But modern pleasure boats have the tanks below fibreglass decks, often enclosed in insulating foam. No way for the tanks to radiate heat like in an airplane. Therefore, no condensation.

The E10 issue adds another variable to this question, but I think the answer is still to store the boat empty.

NEaster - 9/21/2006 10:29 AM

Hi Guys this is my 1st post on this forum after reading for months. I Work for a Marina/Dealership in north east Mass. I work in the service department as a writer consultant, mechanic and rigger. It was my responsibility to research the answer to this question so I contacted our BRP, Yamaha, Merc and Volvo reps to find their recommendations. The 1 thing they all had to say in common was that your tank should be empty. The E-10 will draw moisture from the air and with the fuel systems being open systems the opportunity for this to happen is great. The train of thought being you're going to get condensation in your tank no matter what you do. This being said it's easier to deal with a bit of water in an empty tank then a bit of water in your fuel. Both scenarios require the evacuation of the water by mechanical or chemical means, both of which will be easier with an empty tank. I have no personal experience to speak of in terms of E-10 enriched fuel as this is the 1st season for me and my Whaler with the "improved" fuel, however I though I'd share the results of my research with you.

What you say might make good sense. However, it seems to me that as long as you add sta-bil to whatever is left in your tank now would preserve the gas in there now and changing the 10 micron filters and adding ring free and startron to new gas added in the spring should limit any "water in the fuel problems" next spring.

If leaving gas in the tank causes more water to build up in the tank over the winter......which is what I think you are saying.....then that is good reason to try and achieve empty tanks. Will leftover treated gas in the tank cause more water buildup, over the winter, than an empty tank????

A lot of people feel that as long as gas is treated everything should be ok no matter how much gas is left...however.....they also feel, as you do, that empty is better.

And so the saga continues. If you have any other input please pm me again.

Thanks

Keith
;? ;?

Move to florida---run it all year round. No more problems.