Winter Gives me Gas

[Speedy]

 

 Winter gives me gas. I need some “Winter Advice”. I built two weather-tight, non-heated boat sheds for my pair.

1.       Should I fill the tanks full (very little air space for moisture)? OR ? ...  both tanks are almost full today.

2.       If I top them off to 100% full, should I add a fuel additive to the gas ( I only use High-Test alcohol free gas) but most additives are alcohol based ???

3.       I have good marine battery charger systems to maintain 3 batteries each. Leave them on (good house power service connected) or pull the batteries out?

4.       How many days until Spring

I appreciate your suggestions. Thanks

“Speedy”

[MCF]

Go with the tanks as they are, add some Stabil or some other brand fuel stabilizer to the tanks.  You are using ethanol free gas to temper problems. 

 

Pull the batteries, I would give them a charge about half-way through winter.  If the stay in the boat and you are not charging, disconnect them.

After two recent battery failures-which I have never had in all the years I have been around them I have changed my approach with caveat that it might have been the quality of battery.   I will find that out next spring.

 

Now others will probably disagree but those are my suggestions. 

[Speedy]

Thanks...All the batteries are new this season Marine batteries. 

Speedy

[spoonfed-1]

3 hours ago, Speedy said:

 

 Winter gives me gas. I need some “Winter Advice”. I built two weather-tight, non-heated boat sheds for my pair.

1.       Should I fill the tanks full (very little air space for moisture)? OR ? ...  both tanks are almost full today.

2.       If I top them off to 100% full, should I add a fuel additive to the gas ( I only use High-Test alcohol free gas) but most additives are alcohol based ???

3.       I have good marine battery charger systems to maintain 3 batteries each. Leave them on (good house power service connected) or pull the batteries out?

4.       How many days until Spring

I appreciate your suggestions. Thanks

“Speedy”

Right or wrong I've always filled my tanks to reduce water intrusion from condensation before putting to bed for the winter. Also always added fuel stabilizer and never ever had a problem on start up the following spring.

Edited October 16, 2025 by spoonfed-1

[Silver Fox]

I’ve been told to run my gas down and I’ve never had an issue either.

[spoonfed-1]

13 minutes ago, Silver Fox said:

I’ve been told to run my gas down and I’ve never had an issue either.

Why would you run your tanks down? Just curious.

[13owhunter]

I run stabil marine in every tank simply because the bottle will go bad before I use it all.  I run my gas down too just so I can fill up with fresh gas in the spring.  really not worried about accumulating water as I have a water separator and have never seen any water in there.   When we get a warmish day halfway through winter Ill start both engines and let them get to temp.  I no longer take out the 2 main batteries and bring them inside but Ill plug in the charger a few times throughout the winter.  TM batteries come inside. This has been working for me.....

[Total Chaos]

I empty the tanks and leave my batteries in. I charge them before putting it up. I used to pull them but the last batteries were in there from 2016-2024 with no issues and I never pulled them in the winter. Not only that, they were Everstarts from Walmart. 

[Speedy]

18 hours ago, Speedy said:

 

 Winter gives me gas. I need some “Winter Advice”. I built two weather-tight, non-heated boat sheds for my pair.

1.       Should I fill the tanks full (very little air space for moisture)? OR ? ...  both tanks are almost full today.

2.       If I top them off to 100% full, should I add a fuel additive to the gas ( I only use High-Test alcohol free gas) but most additives are alcohol based ???

3.       I have good marine battery charger systems to maintain 3 batteries each. Leave them on (good house power service connected) or pull the batteries out?

4.       How many days until Spring

I appreciate your suggestions. Thanks

“Speedy”

Thanks Guys. I'm a little "Gun-Shy" about the fuel whereas when I bought the boat, 2 years ago, it had been stored outside in the snow. Brought it to the Marina in Spring for a full tune-up. They found water in the fuel, old tank needed replacing. Had a new custom tank built and sending unit/gauge installed,and water separator filter. Got charged $2,50 a gallon to remove old fuel (30 gallons). Cost thousands for that repair job.  Got the lecture about using only high-test gasoline (Ethanol/Alcohol Free) fuel.  BUT to add gasoline anti-freeze (again alcohol based) for the winter storage.  Oxymoron ? I used to drag race using methanol only; ran cool and made more power than gasoline.

Kind of "Damed if you do and Damed if you don't. LOL

[J.D.]

"Marine PRO is made with 100% safe petroleum cleaning and lubricating ingredients. It can’t harm engine parts, fuel system parts, or seals. Marine PRO is safe and effective in any gasoline marine engine."

 

https://seafoamworks.com/marine-pro-complete-marine-fuel-system-treatment/

Edited October 17, 2025 by J.D.

[Speedy]

Thanks...I just bought some. Going in both tanks this weekend, Speedy

[Silver Fox]

On 10/15/2025 at 9:23 PM, spoonfed-1 said:

Why would you run your tanks down? Just curious.

Someone that knows much more than me, told me to do so. 

[Sk8man]

I store my boat inside an unheated barn but I always keep my 60 gal tank full year round and run Marine Stabil year round so it is always in the fuel line and tank and for the past 22 seasons so far so good.

Edited October 19, 2025 by Sk8man

[Speedy]

Thanks...I agree ....Speedy