This from Boat US on Gas Tank for Winter

Babyboomer

It's fall and many of us are reluctantly having to think about winterizing our boats. Recently, I went to our technical folks asking the age old question, "Should I keep our boat's gas tanks empty or full over the winter?" and realized our best advice has evolved over the years. Here's the latest:

We've always said that a completely empty tank is best, though being boaters ourselves, we know that emptying a larger tank is often nearly impossible. So, in that case, we've advocated keeping the tank full, because it's much less likely that E10 will absorb water if there's little air space in the tank. The answer is not quite as simple as that. Experts from Mercury Marine, Yamaha, the National Marine Manufacturers Association, and others have this advice for storing your boat this winter:

• If you have an outboard, you can disconnect the fuel supply and run the engine until it quits. This gets most of the E10 out of the engine's fuel system.
• When possible, drain the gas tank completely. Note that many marinas that store boats inside prohibit empty tanks because there may be some volatile fumes remaining in the tank.
• If you have an inboard or I/O, or if it's impractical to completely empty the gas tank add a quality stabilizer, fill it to 95% full, then run the engine for 10 minutes to get the treated fuel all through the fuel system.

MarkB

Finally some advise from the manufacturers!

Babyboomer

Just posted what I read

Babyboomer

That was in Boat US Magazine

212rowboat

Not only the pumps... Injectors rely on fuel to pad the valves closing, as well as lubricate them... Also, the fuel actually cools them... They don't like to be ran dry... Injectors are capable of lasting the life of the engine, nowadays- so long as they are treated nicely. Running them dry is about one of the meanest things you can do to them. :-)

212rowboat

Babyboomer said:

That was in Boat US Magazine

Not to pile on, but I read yahoo news a lot, who used to be a decent aggregator before they joined forces with ABC news... Well, maybe even before that, actually.. anyway, I'm humored when they post an article to the affect "why ethanol is awesome for your car!", and a day later post one declaring it liquid evil and quoting contradictory results... It seems folks are commentators now, not reporters.. it seems, also, that opinion is presented as fact more than it should be..

Gas left in lines and in fuel systems can be argued either way.. separation of cocktails in fuel due to aging happens quicker than folks realize, likely, and can leave residue behind that can create blockages or tack up moving parts... Draining and storing can cause gaskets and seals to harden, which could leak or blow out when under pressure.

It's hard to know what's the smart play or not when it can be argued different ways and each is believable and defensible, ya know?

212rowboat

I thought I would add one more thing  're: run 'em dry' ---

I would take every step I could to keep fuel in the rails.. and treated fuel, if possible.. allow those things to drain and then sit, is begging for corrosion and oxidation to happen in a place you can't see, and which will be fed directly into the injectors when you turn the key come spring.

jreau

I always used to leave at least 3/4 of a tank of gas during storage but I hate adding that weight to the boat while it is shore up. The last few years I've been experimenting with leaving less and less gas in the tank. Last year Stored it with half a tank with no water problems at all. This year a quarter of a tank with plenty of dry gas and other storage additives. We'll see what happens.

JoeStang

What does it matter for the weight? if the boat is stored correctly it shouldnt matter at all, IMO anyways.

Dream_Inn

Yes, I can't see where weight matters, just less on the jacks I guess. Mine stays on the lift all winter with full tanks.

Michael T

I run 91 octane. No ethanol. Leave tanks full, add stabilizer. Run engines. Sleep well. MT

MarkB

I'd like to know Boat US's reasoning for recommending a full gas tank for storage. I don't think that is correct. I'd rather keep the tank 1/4 to 1/2 tank, with stabilizer and then add fresh gas in the spring. All gas will decompose over time, and it's best that we can add some fresh gas to run through the engine, rather than have something that's been sitting for 6 to 7 months.

rasbury

For the one day of winter here, I go boating!

Dream_Inn

oh boy, the never-ending debate each fall.  I think there is enough argument on both sides that it will always be a debate.  If it works for you, then it works.  I've done 16 winters of always filling up my gas tank.  It works.  I believe in the no condensation with my gas is important.  I also believe stabilizers work pretty well, so why chance it.  & if nothing else, it's worked for 16 years.  In the spring, it's nice to have a full tank & I use it up before I add anything else in.

Michael T

Changed my mind from my February 2014 post (above in this thread) - after this summer's reading of articles and talking with fellow boaters. I USED to fill the tanks up, add stabilizer, run the engines and store the boat.

I'm going to do it differently this year. Each tank has about 30 gallons of 91 octane left in it - I only use 91 or higher marine gas - never an ethanol blend. There is already Startron gas additive in the gas rom use this summer. I'll add stabilizer, run the engines to normal operating temperature, then change the oil to Mercruiser Synthetic Blend and the oil filters to Mercruiser High Efficiency. Then I'll store it. I will no longer fill my tanks up with gas before storage.