How full does gas tank need to be for Winter storage?

[bruceb58]

Perhaps.....

http://www.boatingmag.com/gear/boatinglab-tests-fuel-stabilizers

LOL...you post what basically is an advertisement?

 

[SeaDooSam]

One thing my mechanic told me which I am not sure is true is he said to fill it like a quarter or half. He said the octane comes out of the gas over time? Is this true. He said there is nothing to prevent it.

 

[wrvond]

First, is your tank metal or plastic? Condensation is not likely to occur in a plastic tank. A metal tank, OTOH is susceptible. So if you have a metal fuel tank, fill it up. This helps the metal stay the same temperature throughout, reducing condensation. Plastic isn't nearly so sensitive to temperature.
Second, if you fill the tank now you are using 2016 dollars to pay for gas that is about $2.45 per gallon (give or take). If you fill it later you will be using 2017 dollars (worth less) to pay for gas that could very likely cost more per gallon. So filling now results in money savings.
If the engine is a two stroke, do fog the engine.
I do recommend draining the carburetor bowl (if you have one), this takes the pressure off the valve seat and reduces sediment in the bowl.
Add your favorite stabilizer/booster/dryer/enzyme/witches brew if you like.

 

[Baylinerchuck]

LOL...you post what basically is an advertisement?

So I guess you didn't read it. If it was an advertisement it would have been one product, no? Readers digest version: all products tested, stabilized E-10, or as they proved in the test, E-7 fuel, by stopping phase separation maintaining octane. Including...(gasp) Starbrite enzyme treatment. Other claims, (snake oil) were not substantiated.
There is a reason they sell non-ethanol fuel at marinas. Since non-ethanol fuel is hard to come by where I live, because my boating domain is not large enough to have pumps, I stabilize the fuel when storing.
I really have no horse in the race, I know it works in all my powered equipment and toys. Without treatment- carb cleaning. With treatment- easy start. That's been my experience, maybe yours is different, I honestly don't know.
Respectively submitted.️

 

[GA_Boater]

Come on, guys. Answer the question with replies to this question - "How full should the fuel tank be for storage?"

Viper didn't ask about the type of gas or any additives, did he? In fact, we have no idea what gas he uses or how he treats the fuel or if indeed he does.

No more talk about the best gas or how to treat stored fuel! Those are saved for another thread! :facepalm:

 

[bruceb58]

One thing my mechanic told me which I am not sure is true is he said to fill it like a quarter or half. He said the octane comes out of the gas over time? Is this true. He said there is nothing to prevent it.

Since the ethanol increases the octane and if the ethanol evaporates out of the fuel you could in theory lose octane. That amount amount of evaporation is very slight though especially considering storage during winter.

 

[bruceb58]

Regarding condensation in tanks, this is a good read.

http://www.yachtsurvey.com/myth_of_condensation_in_fuel_tanks.htm

 

[jkust]

It would be unreasonable for me to run my 60 gallon tank down to nearly empty the exact day I remove it from the lake for the year. I store it with whatever the level happens to be and since it is really never completely full, I just don't worry. Stabilizer for me....in a worst case scenario where life gets in the way and in the unlikely even that the boat ends up sitting unused for some extended length of time. I just heard a commercial for 30% ethanol gas advertising it so you could go seek it out....as though it is something we want. That will be interesting when it is no longer optional.

 

[tpenfield]

I think the full tank theory is one of those things that sounded logical back in the day, but was never really put to the test. If you think about it, it is pretty hard for air to enter the fuel tank during a winter layup, because the tank is full of fumes and fumes are heavier than air. So, what ever small amount of moisture can reside within the tank will not be replenished from outside air, because it can't really get into the tank.

I found a web posting about a guy who has left an empty tank vented to the air for several years, and checked it periodically for moisture. I'll see if I can find it and post it.

 

[tpenfield]

Here is the link that I found. . .

http://www.pbase.com/mainecruising/fuel_tankt_condensation

 

[bruceb58]

Here is the link that I found. . .

http://www.pbase.com/mainecruising/fuel_tankt_condensation

And for those that think a plastic vs metal tank matters....it doesn't either.

 

[Scott Danforth]

fuel will evaporate with an open vent. so no mater what you put in the tank in fall, there will be less in the spring

https://www3.epa.gov/ttn/chief/ap42/ch07/final/c07s01.pdf

so as far as the amount of fuel to put in the tank for storage....... it doesn't matter.

 

[tpenfield]

Yes, and the evaporating fuel goes out the vent line . . . so outside air cannot get in the vent line . . . and moisture from outside air does not get into the tank as some theorize.

 

[thumpar]

I just leave it where it was on the last trip out. Sometimes almost full and sometime pretty low.

 

[hemi rt]

I remember reading that some time back. Not too informative; they basically just parrot whatever claims the manufacturer makes.

I like the review of one product that claims to "improve lubricity." I didn't know gas needed lubricity!

That's so it flows faster in the fuel lines

 

[viper1216]

Thanks for all the awesome info folks. I'll leave it at the current level which will give it some room to expand if needed. Just to answer questions that were asked:

Plastic tank and I use Stabil Marine every time I put fuel in it, and added extra for storage. She's a 3.0 merc so I did not fog it.

 

[JoLin]

That's so it flows faster in the fuel lines

My fuel already flows too fast, thank you :facepalm:

I'm in the 'it doesn't matter how full' camp. I do stabilize the fuel before the last run so the entire system from tank to carb gets treated, but that's about it.

 

[wrvond]

Here is a Service Bulletin from MerCruiser (No. 95-7) that has some interesting information about fuels, stabilizer, and how full your tank should be for storage.
I found it interesting that they recommend draining the tank then adding a stabilizer...

 

[JASinIL2006]

Here is a Service Bulletin from MerCruiser (No. 95-7) that has some interesting information about fuels, stabilizer, and how full your tank should be for storage.
I found it interesting that they recommend draining the tank then adding a stabilizer...

Every time I click on your link, I get redirected to a the main page for a forum called BoaterEd... I'm not seeing the link you refer to.

 

[bruceb58]

I have read that service bulletin that came out in 1995. Not sure something that is 21 years old is really valid anymore.
http://www.boatfix.com/merc/bullet/95/95_07.PDF