---

My son has a 26' CC (Not A Whaler) with a 150 gallon fuel tank. Twin 200hp Suzuki Motors. Here is my question. I am very confused on all of this E-10 gas thing and not sure what do to. Is it better to keep the fuel tank full or empty. I know all about using fuel stabilizers, etc, and I've always been told that there was less chance of moisture accumulation with a full tank, but he has been told that many are having problems with the E-10 fuel causing Havoc with the fuel lines. Should he leave it full or get it all pumped out? Anyone had any experience with this? Problems like this make me so happy to have my little 15.

---

My Parker has a 180 gallon tank. At the end of the season I usually leave 30 gallons or so in it, stabilized with Startron and then top it off with fresh fuel in the Spring, never had a problem while running yammi filters, 10 micron.

You will here all kinds of suggestions but the key is not to let ethanol sit for long, especially if it is un stabilized.

---

In the past I have stored my boat with a full tank (34 gallons) of stabilized fuel.

If fuel with E-10 reaches phase separation, both phases are bad for the motor.

I am waffling on my winter plan.

---

I would prefer to get rid of the fuel or run close to empty, never has fuel been so expensive, and such "Lousy" quality as it has been lately, as "Phil" mentioned "Phase separation" is the problem around water. I too admire the "Sport 15", it's just enough "Boat" for "ME" to handle.

---

We've had 10% ethanol here for at least the last two years. I've been using Sta-Bil with no problems on my old 1990 Merc 115 and have had a few periods of letting the boat sit for at least two or three months.

Just a few weeks ago before my boat went in for re-power, I removed the fuel filter/separator and cut it in half to inspect it out of curiosity. It had been in place at least a year. Though the element looked a little discolored, it was spotless to my surprise.

---

Last year stored all three tanks (300 gals total) on my 305 full, treated with Mercury fuel stabilizer/treatment and Startron. The Mercury fuel stabilizer/treatment actually was double the needed amount because I added the appropriate amount, and then the dealer, not knowing I already added it, put in the same amount. Dealer said the double dose wouldn’t hurt it and I personally believe that it probably helped. Anyway changed the 2 Micron filters at the beginning of the season and have had no problems. I have periodically put new gas in throughout the season (not completely filled) and now the tanks are about 1/3 full each and I plan on keeping them as low as possible for the remainder of the season, treat what gas is left, change the filter again and fill up with fresh gas next season.

---

Last year I stored my larger boat full about 80 gallons and used the marine stabil. In the spring when I changed my sending unit the fuel looked very yellow. Changed my separator/filter and really had no issues, it ran good but with a small hesitation on the hole shot. That went away once I got into fresh fuel. There's always some kind of air gap for condensation to form, you'll never get the tank completely full. This year I think I'm going to leave them empty. If there's no mass of fuel in the tank there shouldn't be a great temperature difference to cause the condensation. also no ethanol to attract water. I'm thinking it's better to dilute a very small amount of old fuel and maybe a little condensation with a lot of fresh fuel in the beginning of the season. I'm thinking I'll drain it as much as possible and run it in the car before winter sets in. Also run the carb dry.

---

The word from the Coast Guard is to keep it either full or dry, but nothing in between.

I have used the "full" technique for 20 years, and have never found even a drop of water in my water separating filter, nor any tank corrosion (which is why you do it in the first place).

The entire issue is aluminum tank corrosion caused by phase separation, not fuel quality.

A partially full tank gives you condensation on the exposed tank surfaces, particularly the top inside surface, which drips into the gasohol, combines with the alcohol to form a highly corrosive mixture, and settles to the bottom of the tank during winter storage, eating your tank.

---

I appreciate all of the feedback and suggestions..........I guess my main question is, because of the E-10 Fuel, do I try to get all of the fuel out of the fuel lines while in winter storage?

---

Tom, What's your average storage period?

---

I second finnegans post....and from the US Navy standpoint.....keep the fuel tanks full to prevent condensation from forming.

I think also a lot has to do whether or not you're storing the vessel in an indoor storage facility or outdoors. Obviously storing a boat outdoors exposes it to greater temperature extremes...thus creating condensation however if you're storing it say, in your garage, the temperature extremes aren't nearly as much and therefore condensation is less likely to form.

---

I keep my Montauk's tanks full, and use Star-Tron. Boat gets used year-round and is stored indoors.

---

It will be stored outside under cover from Nov until probably March. We don't get extreme cold here, but it does get down to right at freezing temps for short periods of time. I also failed to mention that we do winterze with fogging, etc before putting up for the season

---

Larry's method was the standard even with straight gas. If there is no air in the tank it can`t condense into water. Last week I noticed that the E-10 gas in my 6 gallon plastic tank the was filled completely, but sat for 3 months had turned to the color of urine. but found no water in the tank or water separator filter. Not wanting to take a chance I poured the gas in my car and bought more gas for the boat. Car ran fine on it though. Why the color change?

---

I've been told by my mechanic to store the tank empty. Just re-powered by 79 V-20 Outrage with a new E-Tec 200.

---

Forgive my limited experience on this one but I'm curious. I have heard hundreds if not a thousand accounts of how people avoid condensation in their fuel tanks in the off season but I have not seen a condensation problem since the 70s. Even then it was in cars in the dead of winter (-25C to -40C). I live in a cold humid climate on the shores of lake Ontario and I do not fill my tanks for the off season. I do often empty them and burn the gas elsewhere because stale gas is a pain. That being said I also do not have tanks near the size of some of your boats.
Anyone got a condensation story from this millennium?

---

This is a good read.

http://www.yachtsurvey.com/myth_of_co..._tanks.htm

---

Thanks for the read Teach. I did the math and came up with similar numbers on the volume. One thing he overlooks is dew point. You don't need a differential in temperature to hit that. You just need temperature to drop. I always felt that dew point is why on real cold mornings in the 70s the gas line might freeze two miles down the road. ie Gas sloshes around in the tank and washes ice crystals off the tank wall. The crystals then either clog the sump or filter, not sure which, but you get the idea. A couple ounces of methyl hydrate and you were back on the road. Even a bit of water can be a lot of trouble.
New gas blends seem to be much better in dealing with trace amounts of water. That's why I prefer to start my season with fresh gas.
That being said, I still keep a bottle of methyl hydrate in the garage.

---

I fly small airplanes. They insist we keep the tanks topped off after each use. It's the opinion of the FAA that more failures have occurred over the years when the tanks were stored anything but full, than they have when stored full.

YMMV

---

Does aviation fuel contain ethanol??

Full was always the theory before ethanol started about 5 years ago, depending on your location in the country.

Now leave as little as you can and run some sort of stabilization product i.e. startron.

---

I just dropped mine off for winterizing. I left about 10 gallons out of 60 in the tank. I'm also having the dealer add a Racor (60 gph) fuel filer with drain.

---

Very true. Many an airplane have gone down due to water in the fuel tanks. Most smaller aircraft have metal fuel tanks which are more prone to rapid temperature changes. As a result, condensation does form in the tanks. As for aviation fuel having ethanol in it? Per the FAA, here's the chemical make up of aviation fuel:

Aviation fuels consist of blends of over a thousand chemicals, primarily Hydrocarbons (paraffins, olefins, naphthenes, and aromatics) as well as additives such as antioxidants and metal deactivators, and impurities. Principal components include n-octane and isooctane. Like other fuels, blends of Aviation fuel used in piston engined aircraft are often described by their Octane rating. Aviation fuel must be checked daily and before every flight for contaminants such as water or dirt.

With that said, there is no ethanol in aviation fuel.

---

From the Mercury website:

"Is there a simple solution to water condensation in the tank as a result of ethanol?

It is best to maintain a full tank of fuel when the engine is not in use. This will reduce the void space above the fuel and will reduce the flow of air in and out of the tank with changes in temperature. This will reduce condensation on the internal walls of the tank and will limit exposure of the ethanol in the fuel to humidity and condensation.


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."

They have a very complete analysis of the ethanol situation here, and well worth reading. Very informative.

http://www.mercurymarine.com/servicea...thanol.php