Winter Storage Fuel Level

[WChapelle]

I'm a first year boat owner with a Sea Ray 330 Sundancer. I've heard that you should store the boat for the winter with nearly full fuel tanks to prevent condensation. True?

 

[Lazy Daze]

True. This topic was brought up recently (more than once, I believe). Here's one of those threads: http://clubsearay.com/forum/showthread.php?t=23523&highlight=fill+tanks

 

[tobnpr]

There's both schools of thought on this issue.
The other school says that because ethanol actually attracts and absorbs moisture, it can be worse to fill the tanks.
If I did have to winterize, I'd probably add a good stabilizer, and top off the tank(s). Be sure to run the stabilized fuel into the engines before shutting them down.

 

[JVM225]

That was the method years ago before ethanol. Now it is probably best to get as much gas out as possible and fill with fresh gas in the spring. Ethanol doesn't have a long shelf life and can turn crappy over the winter. I don't know if you really want two full tanks of crappy gas in the boat when you go to re-commission it in the spring.
I usually run the tanks down below 1/4 with Stabil in them, and then fill them up in the spring. I also use an additive throughout the year whenever I add gas to combat the bad effects of the ethanol.

 

[Jack F]

Just to muddy things up more.

http://www.powerandmotoryacht.com/maintenance/marine-fuel-additives/

 

[skibum]

Hmmm... That article seems to indicate that the boatyards are telling people what to do.

Mine never said a word and I didn't ask. Do any of you guys have the folks at the marina demanding that you either fill or empty your tanks before winterizing?

 

[JCSAM]

Mine is being hauled out tommorow full tank as I did last year

 

[Jack F]

Hmmm... That article seems to indicate that the boatyards are telling people what to do.

Mine never said a word and I didn't ask. Do any of you guys have the folks at the marina demanding that you either fill or empty your tanks before winterizing?

I was told as empty as possible or 7/8th full, they will treat the fuel.

 

[Lazy Daze]

If you treat (stabilize and E10 fighting stuff) your fuel - which everyone should really be doing year round, IMO - leave it full (or close). If you don't treat it, empty the tank. BUT, you also need to run the engine completely dry so the gas doesn't varnish up anywhere. Or, at least use Stabil in your fogging mix.

However, I'd still be worried about condensation even with an empty tank.

 

[MExcelsior]

Mine is usually half full. I use non-ethanol blend and my boat has a plastic tank! On my old 2001 Crownline, the tank was stainless and I used to always fill it before winter. Someone tell me if I'm wrong, but condensation it seems to me would be more of an issue in a metal tank.

 

[Lazy Daze]

I think the variable here is whether or not the fuel is treated for E10. Based on my personal experience and many, many customers, treating the E10 and leaving full has had no ill effects at all.

I'm going to go out on a limb here and suggest a theory as to why Merc recommends an empty tank with E10: Merc does not have their own E10 treatment. Probably hasn't (or won't) do tests with other manufacturer's products to see if it works. Without doing that, the safest thing (liability wise) for them to do is just make a blanket statement that E10 gas should be removed. Again, just a theory. But, I'll be keeping my tank full of E10.

Aluminum is prone to more condensation than plastic, that is true. Something about the transfer of heat - I'll let someone with a more technical background give the specifics. An example: Were you ever in a boat that had aluminum registers for the AC? The aluminum sweats and drips constantly. I would think it's a similar concept.

 

[gerryb]

Well, I hate to be the bearer of bad news, but Mercruiser says you are wrong. Store full if the fuel is ethanol free, store empty if your fuel contains ethanol. Mercruiser Service manual #30, page 1B-71

Technically, the above is true but here is the complete story from Mercruiser. And of course they have a treatment to sell.


What should be done when storing boats with ethanol-blended fuels for extended periods?

Follow the instructions for normal storage preparation found in the owner’s manual or operations guide. When preparing to store a boat for extended periods of two months or more, it is best to completely remove all fuel from the tank. If it is difficult or not possible to remove the fuel, maintaining a full tank of fuel with a fuel stabilizer added to provide fuel stability and corrosion protection is recommended. It is best to add the stabilizer and fuel treatment to the tank at the recommended dosage, running the engine for 10 minutes to allow the system to be cleaned, shutting off the fuel valve to interrupt the fuel supply and allow the engine to run until it stops, topping off the tank until it’s full to reduce the amount of exchange with the air that might bring in condensation. Do not cap the tank vent and do not fill with fuel to the point of overflowing. Some extra space should be maintained in the tank to allow for expansion and contraction of the fuel with temperature changes. A partially full tank is not recommended because the void space above the fuel allows air movement that can bring in water through condensation as the air temperature moves up and down. This condensation could potentially become a problem.
Mercury Marine Fuel System Treatment & Stabilizer can help maintain fuel systems in storage. It contains oxidation inhibitors to reduce oxidation and gum formation, metal chelating agents to protect metal components from corrosion, water absorbing agents to reduce the presence of free water, and dispersants to help suspend and disperse debris. When placing the boat back in service, be sure to reopen the fuel valve to the engine."

 

[Lazy Daze]

And of course they have a treatment to sell.

Gerry - are you saying that Merc now has an E10 treatment? That's the treatment I was eluding to. I wasn't aware of one, but, hey, I'm not exactly first on Merc's "need to know" list, I guess. :smt101

 

[Lazy Daze]

Huh! Look at that! But, you know, that looks an awful lot like their standard fuel treatment (meaning I'd be curious to know if it's a re-formulation or just the same stuff). Reading through the description it says "for out of season storage". So, which is it Merc? You recommend emptying our tanks, but then promote a product that allows us to not empty the tanks? Sounds like they're CYAing themselves, but also happy to take our money for a product. Oh well, I guess that's why they're a "business".

I'll empty my 6-gallon tanks (other boats) as I've always done. But no way am I going through the hassle of emptying an 85 gallon tank. And a lot of you have a much bigger tank than that!

I'm sticking with what I know works.

 

[rcknecht]

Interesting discussion... I have always put my boats away full and treated... Makes me feel good to know that I am not looking at an $800 bill in May when we first use the boat... Plus it is easier to fill up a tank than completely emptying a tank... I have never had a problem with bad fuel...

 

[Lazy Daze]

Here's the thing though, it would take a total of 8 bottles of Mercury's treatment to treat my fuel for a year. 8 X 8.46 + sales tax = $72.42

Yeah, I don't even use the Merc stuff. I use Startron throughout the year (it's less expensive per gallon than the Stabil). But I also use Stabil (red) over the winter. Startron is supposed to be a good stabilizer, too. But, I guess I'm just so used to the name brand of Stabil that I feel better using that for the winter in addition to the Startron.

I wonder how many "should we fill the tank" threads are now on this forum? :smt101

 

[Woody]

Condensation can form on gas tanks made of either material, plastic or metal. Because of the difference in the rate of heat transfer condensation would likely form on a boats metal tank more often, all else being equal. An example would be that condensation usually forms on the glass or metal portion of a window not the wood. The water vapor can also condense on the surface of the fuel itself inside the tank.

IMO spring fuel problems are more a result of the activity in the previous season than just what happens during the storage period. During the boating season I always top off and keep tanks full. A typical weekend I’ll run 1+ tanks of fuel. While that can be hard on the wallet I feel I’m less likely to have fuel problems than those who’s tanks are half full all the time because they only burn a tank a month. I use a fuel treatment a few times during the season and in prep for winter storage with a full tank. I change my fuel filters at least annually. I avoid when possible taking fuel the same day a marina has rec’d a fuel delivery. Last year my boat sat for 8.5 months(that was a long one), typically it is around 7 months and I haven’t had any fuel problems yet.

 

[glocklt4]

Is hard starting, rough idle, but good WOT performance a sign of moisture in gas? I had a slight issue with this early on in the season last year, but I think it went beyond 1 tank of gas. Though I guess if there was moisture then it could have hung around for 2+ tanks without too much difficulty because i don't tend to let my tank go less than 1/4-1/8 tank.

If that is a sign, then I may try leaving my tank empty this year. Last year I regular Stabil (non e10 balancing) in e10 gas (not sure were to be ethanolless gas here).

 

[glocklt4]

Another question since some of you drain gas... what do you do with bad gas? I have a couple small gallon jugs from lawn mower and blower gas over the years that are still sitting. Not even sure that the tank will be any good now, ha, but I need to get rid of that crap. I don't have any places for a bonfire either

 

[Uplate]

We are fortunate in that our marina does not sell Ethanol Gas. I still use the Startron product even though I boat year round. Certainly less hours during the winter, but I still get her out and run the piss out of her once every two weeks at least.