End of season, minimize fuel left in tank or fill up ?

I have heard arguments on both sides..... some say you should have as little fuel as possible in your tank, then add stabilizer to the fuel and winterize the engine... others have said to have a full fuel tank, then stabilize and winterize ( to minimize the available space for condensation/water separation in the tank).

I have a plastic tank and have tried both methods... mostly by chance. I haven't had any problems either way.

What is the best way to go.... little to no fuel in the tank or fill up the tank before stabilizing ?

Re: End of season, minimize fuel left in tank or fill up ?

Most fill up because the price will be more in the spring, I kind of agree with the condensation deal but with the proper stabilizers I've never had a problem either way myself.
Grub

Re: End of season, minimize fuel left in tank or fill up ?

I leave what is left in the tank and stabilize it. Sometimes it is full and sometimes it is low..depends on the weather before winter kicks in.

Re: End of season, minimize fuel left in tank or fill up ?

The argument for as little fuel as possible is because stabilizer does not guarantee no phase separation, so if you end up with a bad tank after the winter, you have very little to dispose of via a hazardous waste company. Probably safe with a full tank for a few months, but if you are laying up now, I assume you have at least 9 months of downtime ahead of you. That is a long time.

Re: End of season, minimize fuel left in tank or fill up ?

Jasoniboat said:

I have a plastic tank and have tried both methods... mostly by chance. I haven't had any problems either way.

What is the best way to go.... little to no fuel in the tank or fill up the tank before stabilizing ?

Click to expand...

Sounds like you answered your own question........ You will never get a consensus.

Re: End of season, minimize fuel left in tank or fill up ?

We regularly leave a number of gas cans at our cabin in Ontario. They sit at least 8-9 months; on occasion, we've had gas sit over two seasons (i.e., a year and a half). Some are in full cans, some in partially full cans, but all get treated with marine Stabil. All purchased in the summer in the muggy Midwest. All 10% ethanol.

We've never had any trouble with this gas, either in two-stroke outboards, chainsaws, four-stroke pump engines or generators, or even in our Mercruiser V8. No phase separation, no turning to varnish... I'm now of the opinion that the dangers of "old" gas, especially gas with ethanol, are generally overstated. I imagine gas that's three or four or five years old is a different story, but I have a hard time believing there is any danger in properly-treated and -stored gas for a year or less.

Jim

Re: End of season, minimize fuel left in tank or fill up ?

Years ago outboard mfgrs even recommended stabilizers for storing fuel over the winter, back when gas had lead in it and all that nasty stuff. As Musky stated you will never get a consensus. You have the die hard redneck professing useless snake oil and the dedicated user that has proven to himself that they work, like me. Gotta make your own decision.

Mark

Re: End of season, minimize fuel left in tank or fill up ?

I think a lot depends on where the gas is stored... if in a sealed can with the vent closed, it will last a long time, even without stabilizer. If in a permanently installed tank in the boat, there will be a vent letting condensation in/out and because of the water vapor and the ethanol in the fuel, you are more likely to get fuel separation.

Re: End of season, minimize fuel left in tank or fill up ?

Fill 'er up, storage dose of Stabil, tape over the vent. You would have to have a lot of moisture in your fuel to get it to separate out, especially using marine formula stabil. Getting to that level of moisture would be more likely if the vent was breathing and there was air space in the tank, combined with a smaller volume of fuel to absorb it.

Re: End of season, minimize fuel left in tank or fill up ?

Empty or close to it.

Re: End of season, minimize fuel left in tank or fill up ?

It won't phase separate unless there is moisture in the tank beforehand.
It won't get moisture from condensation if the tank is full (or sits in the rain with the cap off)
E10 is the devil, or is it? Regular gas will let the water sit in the bottom (not separate, because it wasnt together in the first place....LOL) E-10 will absorb a certain amount of water thus its better in that regard.
Condensation was always a potential problem.
Owner's manuals way back in the 1950's said keep the tank full and stabilized.....hahahah Stabil is only a new thing to the youngsters in town.

Bottom line if you store the boat in adverse conditions, fillerup. If you have a dry garage, it won't matter anyway.

Re: End of season, minimize fuel left in tank or fill up ?

Jasoniboat said:

I have heard arguments on both sides..... some say you should have as little fuel as possible in your tank, then add stabilizer to the fuel and winterize the engine... others have said to have a full fuel tank, then stabilize and winterize ( to minimize the available space for condensation/water separation in the tank).

I have a plastic tank and have tried both methods... mostly by chance. I haven't had any problems either way.

What is the best way to go.... little to no fuel in the tank or fill up the tank before stabilizing ?

Click to expand...

From the mercury marine site
http://http://www.mercurymarine.com/service-and-support/storage-and-maintenance/faqs/mercruiser/?category=winterization#EthanolStorage
What should be done when storing boats with ethanol-blended fuels for extended periods?
Follow the instructions for normal storage preparation found in the Operation, Maintenance & Warranty manual. 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, run the engine for 10 minutes to allow the system to be cleaned, shut off the fuel valve to interrupt the fuel supply and allow the engine to run until it stops, and top 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 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.

Re: End of season, minimize fuel left in tank or fill up ?

I think it depends on how long your off season is, and how much you use the boat. If it's only 3 or 4 months, and you use the boat a lot, then it doesn't really matter how much gas is in the tank - but if it's 6 or 7 months, and you don't use the boat much, then leave it as empty as possible, or you'll end up still using this years gas at the end of next year!

Re: End of season, minimize fuel left in tank or fill up ?

I don't much care about anyone's opinion on this matter. I'm pushing 60 years old, and my entire adult life has revolved around many many MANY gasoline powered engines. Motorhomes, cars, trucks, motorcycles, ATV's, boats, go-carts, tote-gotes, snowblowers, lawnmowers, generators, weedeaters, snowmobiles, post-hole diggers-- some of which sit around for years with the same gas in them. My wife's car hasn't been started in months, the tank's half full, but I know for a fact I can go out right now and it'll fire right up. The gas in our Party Cruiser's generator fuel tank is 8 years old, and the generator still starts and runs fine. The gas in the 130 gallon toy tank in our house boat gets 30 to 40 gallons a year added to it in the spring to top it off, and the 60 gallons that was in it when we bought it was 6 years old, and we've owned it 7 years. I've never stabilized any gas, and I've never had gas "go bad". A couple of months ago I did find water in a gallon of gas I bought for my mowers, but that was from the station. Don't know if it was from alcohol absorption, condensation, or just what, but that was brand new gas.

Anyway, my answer to the question at hand: Do It However You Want, Because It Doesn't Matter.

Re: End of season, minimize fuel left in tank or fill up ?

Empty... Gas can't go bad if you haven't bought it yet. The condensation thing is more of an old wives tail than anything else, it really doesn't make that much of a difference full or empty.

Re: End of season, minimize fuel left in tank or fill up ?

op2:

Re: End of season, minimize fuel left in tank or fill up ?

NYBo said:

op2:

Click to expand...

What Bob said

My off season runs 6-7 months through the winter. I stabilize (Marine Sta-bil) and store the boat with whatever level is in the tank at the time it gets hauled. It's been nearly empty, nearly full and everything in between.

Re: End of season, minimize fuel left in tank or fill up ?

the answer to your question is the answer to all boating questions: it depends.

Obviously if there's no gas in the tank it can't go bad. So dump that six gallon tank into your car. But an 80 gallon tank, half full and below decks? not so easy. That affects your decision.

Obviously age is a factor: did you fill up in May and only use the boat a few times? Your gas starts old; not the same as filling a 1/4 tank in September and starting with new gas in storage.

Did you "stabilize" the gas when you bought it? you can't fix gas that has turned.

An empty plastic tank won't rust, obviously; a bare metal tank bottom might. That can affect your decision.

Condensation and other moisture issues are regional. The guys in the Canadian midwest have fewer issues than the guys in Alabama. That is one of the primary sources for the opposing "opinions." They cannot be contrasted because they are both right--but only one is right for you.

Likewise a sealed can and a vented inboard tank are as different as chalk and cheese on this issue. Ignore that comparison.

Anecdotal evidence has limited value. One guy has no issues doing nothing and his next door neighbor has constant problems doing nothing and HIS neighbor does all the "right stuff" and has no problems and HIS neighbor does all the right stuff and has constant problems. Those individual experiences don't tell you doodly.

Talk to a marine mechanic in YOUR home town to get the best answer.

Re: End of season, minimize fuel left in tank or fill up ?

^ +1 .....what he said. now please pass the popcorn

Re: End of season, minimize fuel left in tank or fill up ?

+2 HC....
I forgot that not everyone has a 50 gal. below deck tank:noidea:

I do put Stabil in every gal of fuel I buy. That way I don't have to worry if the boat doesn't get used for a while, or if I wind up with a nearly full tank at the end of the season. Last summer for example, my Dad had a bad accident and I only put about a half tank through the boat all season.