Most are recommending you keep gasoline as low in the tank as possible. This is because of the ethanol that is in a lot of the gas these days. The ethanol absorbs water out of the air, the theory is more gas=more ethanol=more water. Car fuel tanks are sealed for the most part, where as boat tanks are vented to the atmosphere so there is more air exchange and more chance to absorb water.

 

Most are recommending you keep gasoline as low in the tank as possible. This is because of the ethanol that is in a lot of the gas these days. The ethanol absorbs water out of the air, the theory is more gas=more ethanol=more water. Car fuel tanks are sealed for the most part, where as boat tanks are vented to the atmosphere so there is more air exchange and more chance to absorb water.

There are many differing opinions on this. You need to hear the rationale on all of the opinions and make a decision based on your circumstances. Many of the posts here have given their rationale, which all have merit.

I would disagree with this post, however. I have not seen that most are recommending to store empty. I agree that Ethanol absorbs water out of the air. That fact supports storing tanks full as there is less air in the tank. A vented full tank has less exposure to air than near empty tank. An empty tank will condense water on the walls as the temperature swings. That will drop into your remaining fuel and result in a higher concentration of water in your fuel than if your tank was full. Don't forget that metal tanks will also corrode when exposed to the moist air. A good stabilizer will minimize phase separation and corrosion. Six months is not a long time, especially when using stabilizer. I would also argue that the fuel you buy in the fall is "'fresher" and less expensive.

My recommendation is to top it off and add the appropriate amount of Stabil or Startron.

 

The marina where I winterize my boat requires the gas tanks to be full.

 

No e10 here. We store full.

 

Our marina says full. Besides, you never know what gas prices are going to be in the Spring.

 

No e10, fill them. If there is e10 empty them! I've never really paid attention to filling or emptying the tanks. I've usually left them empty and then filled with fresh fuel in the spring. We have a very dry climate here so that probably helps. In 22 years of boat ownership, I've never had a fuel related problem with a boat I've stored over the winter. Add Stabil and make sure you run it through the carbs and you're good to go.

 

Mine: Empty or as close to empty as I can get... Also add stabil... and tape over the vent to minimize water from our rainy winters. Keep it empty Especially now that e10 is all over the place and it is not good to store over 3 months (if it was fresh when you bought it).

As far as buying from a marina where gas was sitting over the winter, doesn't the fuel get drawn from near the bottom of the tank and not the bottom itself? If that is the case then, you should not get water that separated out? Or am I wrong on that?

I know my in ground oil tank sits in the ground at an angle to allow water, etc to sit near the bottom. I only have about 900 gallons out of a 1000 gallon tank that is useable. :huh:

 

As far as buying from a marina where gas was sitting over the winter, doesn't the fuel get drawn from near the bottom of the tank and not the bottom itself? If that is the case then, you should not get water that separated out? Or am I wrong on that?

You're right, and, of course, it depends on how much separation happens (if any at all). But, the other downfall to phase separation is that the ethanol is used as the octane improver. So in this example, you would now be filling up with gas that is of a lower octane.

How likely is either of these scenarios in reality? I don't know. But those are the two main problems -- you either get water in your tank, or gas with not enough octane.

I'm still not completely sure what to do with my tank over the winter or which method is best. So far, over the past winters, I have been treating it and keeping it full. Knock on wood...:smt001

 

No e10 at our Marina but I start running Sta-bil Sept. 1st and try to keep the tank full as possible. Also, be sure to run the generator awhile so the treated fuel gets to it also.

 

Diesel was mentioned at the beginning of the thread - I'm curious, does everyone agree that for diesel it's best to keep the tank full over the winter? I read somewhere that doing this reduces moisture, not sure if that's true.

Thanks,
Jason

 

:smt001empty with a good fogging.:smt001

I always thought for gas engines winterizing you should fill tank. Was bored the other day and read the West Marine Winterizing check list and they said empty tank for gas engines, fill tank for diesel.

Thoughts?

 

It is the air space that allows condensation. Store with full tanks and stabilizer!

 

Something else I just remembered. I believe the recommendation to keep the tanks full is more important when you have an aluminum tank as the aluminum will cause more condensation than a polyethylene tank. That being said, I'll still be keeping my poly tank full. I'll stick with what's worked for me over the years.

Besides, that makes sense (what some of you are saying) about it being the amount of gas (or lack of) in the tank that is going to cause the condensation - not the fact that the tank is vented to the atmosphere. I mean, whether the tank is full or the tank is empty, it's still vented. But, by having less gas in the tank, the potential for greater temperature variation within the tank is increased.

Treat the gas with Startron or Marine Stabil to combat the potential problems with E-10. CRC has recently come out with their own "E10" stabilizer, too.

Diesel: Keep it full, too. Use a good anti-gel/anti-microbial, as well.

 

I add e-10 stable and fill the tank. Never had a problem. The boat is store in a 30 x 60 unheated pole barn during the winter, so that in January I can wish the ice and snow would melt and we can be on the water again in the mid 80's.

 

My Mercruiser Manual says:
Preparing your power package for storage.
FUEL TANKS

1. Fill the fuel tanks with fresh gasoline (that does not contain alcohol) and a sufficient amount of Mercury fuel system treatment and
stabilizer to treat the gasoline.

2. If the boat is to be placed in storage with fuel containing alcohol in the fuel tanks (if fuel without alcohol is not available):
Fuel tanks should be drained as low as possible and quicksilver gasoline stabilizer for marine engines added to any fuel remaining in the
tank.

 

They have to say something, so you get a one size fits all answer. There are too many variables to accept that answer: dry climate/wet climate, temp constant/temp variable, inside/outside storage, metal/plastic tanks, short/long term storage.

 

Since E10 will absorb moisture in your fuel tanks the ideal situation for winter storage is to completely fill the tanks and add some fuel stablizer for added protection. An empty tank creates more condensation in the tank and the ethanol attacks the water that could lead to "phase separation" . Once you get into this situation the fuel needs to be discarded. E10 is an awful motor fuel for boaters. PS the oil industry hates it too!

 

IMO - full with Stabil works for me. I think there was a poll about this but I can't find it now. It think it asked if anyone had problems storing a boat with ethanol.

I have had both carburated and fuel injected boats for about 10 years now and fill them (e-10 because thats what is everywhere around here). Winterize in October and start them up in May - never had a problem.

 

I scheduled my winterizing and storage with the dealer and asked about this, they said as empty as possible if not 7/8th full, they will treat the fuel.

 

I store with a quarter tank or less, always have. I treat the fuel with Pri-D, and I have never had a problem. Did the same with gasoline powered boats. Never had a problem. Condensation is not an issue, unless you have HUGE temperature changes in a very short period of time. Do your tanks sweat in the summer? No, so why would they in the winter? Besides, don't need the extra weight while up on the cradle...... Just my opinion.

 

Just an FYI: sweating used to be more prevalent when tanks were made out of aluminum (some still are). With the popular use of Poly-E, the sweating issue is less of a concern.

 

Out of [FONT=Calibri, Verdana, Helvetica, Arial]curiosity, have you ever seen a tank actually condense/sweat? They will condense/sweat on the outside as much as the inside, and I have never seen that. Ever. I've always been a Midwest boater, so we have the temperature extremes. Most water makes its way into the tanks via bad fill o-rings, poorly designed vents, etc.


[/FONT]

 

Are you looking for the You Tube video that shows water forming in ethanol fuel? If so, remember my post is discussing diesel fuel, not gasoline......

 

Are you looking for the You Tube video that shows water forming in ethanol fuel? If so, remember my post is discussing diesel fuel, not gasoline......

That's the one.

I agree, if I had diesel, I would store empty, more to prevent growth and gelling.

But, the original poster was asking about gasoline.

 

Never seen it on the inside (kind of hard to do). But, I absolutely have seen it on the outside.

I sort of thought the bigger boats might still have aluminum, but wasn't sure - thanks, Mike.

Used to be all boats had either aluminum or, even worse, fiberglass. The poly is nice in some ways (like helping to eliminate sweating), but they're a pain to try to fix.

The fiberglass glass ones do not get along with ethanol - the E will eat away at it. :wow:

 

The fiberglass glass ones do not get along with ethanol - the E will eat away at it. :wow:

This is not true with newer resins. Tiara still builds fiberglass tanks. Most of the underground steel storage tanks at gas stations around here have been dug up and replaced with fiberglass tanks.

 

Based on the posts...I'm gonna fill mine half way!

Not really, always full and run the Stabil through.

I now see West Marine has a marine version...anyone use it?

 

Alot of reading here...

http://clubsearay.com/forum/showthread.php?t=2047

 

If you store the tanks low on fuel and you get interior tank wall condensation, it will require much less condensation/water for the E to saturate the small amount of fuel and hence, the phase seperation process to occur.

If the tanks are full, then you will have less exposed inside tank wall to form interior condensation. And, with full tanks, you will need magnitudes more water to saturate the E to cause the phase seperation.

Should the phase seperation occur to a tank low on fuel, you can't just add more good fuel to reverse the process....the tanks have to be pumped to get rid of the bad fuel.

IMHO, the idea is to avoid any phase seperation at all.

Other than completely empty, I would store my E-10 gasonline tanks full......which is what I did when I had my 380DA and E-10 fuel.

 

IMO fill them up diesel or gas, add appropriate fuel additives. I wonder if those that have fuel/water/separtion problems in the spring are really having problems due to water already accumulated and not just from condensation during the layup.

 

New Twist: What about the weight of a full tank of gas resting on jack stands?
It seems like a great deal a pressure that’s not evenly distributed.

 

Very insignificant compared to the weight of the boat. Nothing to worry about there.

I know the OP was mainly concerned about gas, but I would fill up diesel, too.

I had the engine out of my Burb for a good year (March through the following May). Unfortunately I wasn't able to fill it before pulling the engine, it was about 1/2 - 2/3. BUT, I always treat with a good lubricity/anti-gel/anti-microbial additive. In fact, for the few extra pennies it costs, I usually double-dose. Got the engine back in - started right up - ran most of that tank out with absolutely no problems. When I changed the fuel filter, it looked normal.