gas storage. Tank full or empty?

[robert53a]

Do I store my boat's gas tank full or empty for the winter, and how long will modern gas stay viable in the tank with added stabil? Thanks any advice would be appreciated. I have a 2010 smokercraft tracer and I'm trying to keep it up as much as possible........Robert

 

[Home Cookin']

Re: gas storage. Tank full or empty?

this topic debated interminably.

If "modern gas" means E-10, untreated it starts falling apart 28-90 days after purchase, or never, depending on conditions and who you ask.

Treated gas should be good for at least the 6 months winter; some will say up to 2 years.

Obviously, completely empty and dry eliminates any problem, but few people mean dry when they say empty. So between leaving an inch or so or topping it off, those who believe the fuel attracts water or otherwise deteriorates, topping it off is better.

If you are storing at a marina or other storage facility, it may have its own rules.

 

[Beefer]

Re: gas storage. Tank full or empty?

Yes

 

[bruceb58]

Re: gas storage. Tank full or empty?

Yes

+1 on Beefer's opinion.

 

[1980Coronado]

Re: gas storage. Tank full or empty?

+2...never worried about it.....put enough stabilizer in for what's in the tank and store it.

 

[BRICH1260]

Re: gas storage. Tank full or empty?

I put mine away with 3/4 tank and overkilled with Stabil.

 

[jacoboregon]

Re: gas storage. Tank full or empty?

2-cycle outboard or 4-cycle I/O or outboard.
I agree with the above stated for 4-cycle motors, but would recommend an 95% full for 2-cycle if you aren't going to be using it for more than 2 months, as per my mechanics advise and my personal experience. My understanding is even treated, gas with ethanol still absorbs water over time, as the ethanol is not removed by treating and is hygroscopic. Keeping the treated tank of fuel 95% full removes the amount of air available in which to absorb the moisture. Make sure the cap is tight and any vents closed. 95% vs 100% allows for expansion.
Check out this page of the Oregon State Marine Board on E10 gas and boats:

http://www.oregon.gov/OSMB/news/E10.shtml

 

[Alwhite00]

Re: gas storage. Tank full or empty?

Fill mine and add Stabil.

LK

 

[Philster]

Re: gas storage. Tank full or empty?

Mercruiser says 9/10 full with stabilizer.

Mercury Marine says empty (if practical).

Both their sites say partially full w/out stabilizer is the worst.

Ain't boating fun?!

 

[cr2k]

Re: gas storage. Tank full or empty?

since it's the surface of the gas that condenses water it really doesn't matter if it's got an inch or almost full the surface area would be the same.

 

[Philster]

Re: gas storage. Tank full or empty?

You talking to me or Merc?

 

[DBreskin]

Re: gas storage. Tank full or empty?

since it's the surface of the gas that condenses water it really doesn't matter if it's got an inch or almost full the surface area would be the same.

It is my understanding that water condenses where warm air meets a cold surface. If the gas and air in the tank is warm (relatively speaking, above freezing) and the outside temperature drops to cool the walls of the tank, it's the tank walls that will condense moisture from the air. Filling a tank minimizes the exposed tank wall area and therefore minimizes condensation.

In my case, I have an I/O with a in-floor tank. The tank is surrounded by flotation foam and covered by a blanket of plywood and carpet. The temperature of the tank and fuel isn't going to change rapidly enough for me to be concerned about condensation. I put in some stabil and refuse to worry about it.

 

[robert53a]

Re: gas storage. Tank full or empty?

Thanks for all the input! The boat is stored in an attached garage. The tank is 2/3 full of gas from the summer and laced good with stabil. I think I'll be OK. I appreciate all the feed back...Robert

 

[jacoboregon]

Re: gas storage. Tank full or empty?

since it's the surface of the gas that condenses water it really doesn't matter if it's got an inch or almost full the surface area would be the same.

That's only partially true... While it absorbs from the surface, the more volume of air available the more volume of water that is available for absorbtion.

 

[Home Cookin']

Re: gas storage. Tank full or empty?

"you're both right"
There is the condensation from tank walls--that's one source of water and that is basically dripping water. I can't see how stabil can do anything about that.
there is ALSO water absorbed from the surface, so true in that regard, full/empty doesn't affect surface area. Myunderstanding is that stabil "covers" the surface to block that absorbtion.
But moving away from surface alone, an almost empty tank presents more air in the tank and therefore more moisture. We all know that boat tanks, being vented, breathe like a lung.

 

[Philster]

Re: gas storage. Tank full or empty?

What I want to know is why Mercury Marine and Mercruiser have two different winterization procedures!

 

[ErikF]

Re: gas storage. Tank full or empty?

I really don't worry about mine, with my smaller boat I have two six gallon tanks, at the end of the season one is usually empty and the other is maybe half full. I don't think it's enough to worry about, I've never had an issue burning up the old gas at the beginning of the next season.

My larger boat has 25 gallon capacity with twin tanks, they're empty this year because I'm restoring the boat and pumped the fuel into my truck, if they were full I'd probably just add Stabil and let them sit.

 

[paultjohnson]

Re: gas storage. Tank full or empty?

I feel its more important to try to find non oxygenated fuel, then worrying about the level of the tank. I store mine with about a qtr tank of non oxy premium, with stabil. Then fill er up in the spring with fresh fuel before my first spring start. Always good to go.

 

[solar7647]

Re: gas storage. Tank full or empty?

I say empty, gas prices are too high to fill a tank with it and just let it sit for the winter! Then you don't have to worry about stable or water getting in it.