Question for the folks with gas engines

[denpooch]

I hear many different reasons for how much or how little stabilized gasoline to leave on the boat during hibernation.
I have been leaving about 3/4 of a tank of fuel. I am doing this because it is what the Marina did where I purchased the boat. I don't know why they do this.
What is your approach and why. Thanks.

[mjk1040]

The more fuel in your tank the less condensation area for moisture to develop in your tank if the temperature in your area during lay up fluctuates a lot from warm to cold. A good fuel stabilizer is also recommended since the gas these days tends to break down, especially if you have to get fuel with ethanol in it. You don't want them completely full during layup as the fuel may expand on a hot day and run out your vents.

[Midnightsun]

Before ethanol, the norm was full tank, now the argument is ethanol attracts water so less is better. Who knows, this sort of like the Chevy/Ford thing. Popcorn anyone?

[vineyardgray]

I have heard both debated and I decided to make up my own mind on the subject because there was no consensus. Besides, my 454's have fuel/water separation filters, which I hope means it doesnt matter that much

[Viper]

Source of the post Before ethanol, the norm was full tank, now the argument is ethanol attracts water so less is better.....

BINGO

[tomschauer]

My practice, since the introduction of ethanol, has been to pull the boat into the lift well on fumes, with just enough fuel to get to the fuel dock upon launch. I have never used a fuel treatment or stabilizer. Maybe just lucky? I replace my fuel filters every third year and haven't had an issue. But I always have 2 sets of spare fuel filters on board just in case.

[RGrew176]

My preference is to have the tanks as near full as possible. Because there can be some fluctuation due to temps I fill both tanks then take the boat out for one final spin to burn off some fuel. Generally I like to burn off about 4 to 5 gallons from each tank. Then I don't worry about expansion and contraction. When my boat is shrink wrapped they generally wrap down to the tape line. That covers the fuel vents and should for the most part keep a lot of the moisture out.

[buster53]

I took an engine maintenance class through the US Power Squadron some years ago. Class was taught by the owner of a small, but respected boat dealer here in town. His thoughts on the matter...the quality of gas these days is way less than in the past. Also, a couple ounces of condensation isn't nearly as bad as having a tankful of old, stale gas. Remember, fuel treatments can only extend the life of gas so far.
I have always winterized with 1/4 tank or less, both diesel and gas, and have never had problems.

[bud37]

Good question, two camps I guess......in years past I have always treated the gas at maybe 1/2 tank or less and never had trouble , and in the spring you could top it with fresh gas, with nice Racors that could be drained it worked fine.
But that was different fuel than we have now, the shelf life used to be around 90 days, now my understanding is around 30. You get full tanks of this fuel and something comes up and no boat usage = you have got a problem, worse if it has some ethanol , yikes...IMO

This year I had to have around over 3/4 in two tanks pumped out ( interesting colors ) and disposed of, as it was basically old mixes and nowhere to put fresh fuel. My thinking now, will be to have the tanks as MT as possible, then all fresh in the spring. Just trying to keep those fancy MPI injected engines from detonation under load.

Twice in recent years I have seen gallons of fuel blowing out of boat vents to the ground on temp swings. How the boat is blocked will also have an affect on that happening. Think flying cig butt here.

For those of you that use their boats all year, ya must think we are nuts for going thru all this, I am beginning to agree. Gone are the days when we could take out our old fuel and run it thru the truck over the winter....

[pepmyster]

I know this conversation all too well. People always ask my opinion and there is nor exact correct answer. Some people leave it near empty of near full with no problems. Will I argue their choice? Not on your life. I'm taking ours out on Friday morning and I have between half and 3/4 fuel. I'm going to top it off, as close to full as not to spill. Always have done this. Then in the spring, the boat is full and I don't have to worry about the price of fuel for awhile. But, That's just me.