Winterizing - How much fuel to leave in tank

Massawippi

Cadet
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Jun 6, 2004
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10
I really find that there is ton of info on this board and I was wondering if somebdy could help me with this one. <br /><br />This is the first year I've owned a boat and it is getting time to take it out of the water for the winter. Is it better to leave as little gas as possible in the tank or should I leave more?<br /><br />Thanks!
 

crazy charlie

Vice Admiral
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May 22, 2003
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Re: Winterizing - How much fuel to leave in tank

Fill it up to the point where it will be full but wont come out the vent if tilted a bit.The less room you leave in the tank---the less condensation there will be- and visa versa.Make sure you add stabilizer.Charlie
 

ZmOz

Captain
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Aug 13, 2003
Messages
3,949
Re: Winterizing - How much fuel to leave in tank

Yeah, fill it up. Less air means less room for condensation, and the more gas you have, the slower it goes bad. You should use premium though, even if your boat doesn't need it, because as it sits it looses octane.
 

skategoat

Seaman
Joined
Mar 29, 2004
Messages
74
Re: Winterizing - How much fuel to leave in tank

On the other hand, if your gas contains ethanol, the conventional wisdom is to drain the entire system. Ethanol will corrode rubber components including the gas line.
 

crazy charlie

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Re: Winterizing - How much fuel to leave in tank

Skategoat,never heard of draining the entire system before?????? Charlie
 

POINTER94

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Re: Winterizing - How much fuel to leave in tank

Ditto Crazy charlie, and make sure you use a fuel stabilizer in the right amount. <br /><br />ZmoZ I never heard that fuel loses octane, is there a rate that can be measured or is it one of those time/temperature type of things?
 

crazy charlie

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Re: Winterizing - How much fuel to leave in tank

Many people THINK that the fuel looses its octane count because they usually get a ping or unsmoothe running come spring when what it really is ,is that the fuel burns like crap after it has been stabilized.The second tank is always better.Charlie
 

KM2

Chief Petty Officer
Joined
Oct 15, 2003
Messages
556
Re: Winterizing - How much fuel to leave in tank

I fill it up to reduce the condensation build up as suggested. I don't top it off for this reason. Gas expands when warmed up, fill to top in fall (cool outside) come spring gets warm out and fuel spills out the vent or gas cap. It's a mess and a fire hazard. <br /><br />I use non ethanol premium (hard to find in MN) and stabil. I have heard several times that gas looses octane but can't remember were and if a good source. Anyone know for sure?
 

red10

Petty Officer 2nd Class
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Dec 11, 2003
Messages
175
Re: Winterizing - How much fuel to leave in tank

you can get it up north at alot of stations, look on the web and they list the stations that carry non-oxygenated gas usually its premium
 

POINTER94

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5,031
Re: Winterizing - How much fuel to leave in tank

KM2<br /><br />I experienced exactly what you described when I filled my tank in the fall and we had a freak couple of 90 degree days in April this year and the gas shot, no lie, 4-5 feet like it was coming out of a hose, from the vent and fill cap.<br /><br />Won't make that mistake this year...<br /><br />Red10, is there a web site you can recommend for gas stations with the non-o2 fuel?<br /><br /><br />Thanks
 

mattttt25

Commander
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Sep 29, 2002
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2,661
Re: Winterizing - How much fuel to leave in tank

i've heard both sides, so i'm convinced it doesn't matter. add fuel stabilizer as directed and top off the tank next year before going out.
 

ZmOz

Captain
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Aug 13, 2003
Messages
3,949
Re: Winterizing - How much fuel to leave in tank

Yes, gas loses octane as it sits. That is a fact. Search google if you don't believe me.
 

swist

Senior Chief Petty Officer
Joined
Jul 1, 2004
Messages
678
Re: Winterizing - How much fuel to leave in tank

There are other issues. My boat has a 100 gal tank. I would rather not spend a lot of money to fill the tank so I can have a boatload of stale gas in the Spring that I have to put up with. It also weighs 600 lbs when full which is extra weight to deal with when towing launching in the Spring.<br /><br />I think I'd trust my water separator to deal with the condensation and leave the tank relatively empty.
 

zzub

Seaman Apprentice
Joined
May 12, 2004
Messages
32
Re: Winterizing - How much fuel to leave in tank

There is a safty consern also, A full tank will burn and emty partly filled tank could explode due to fumes. Check with the Coast Guard & see what they rccomend ??
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,320
Re: Winterizing - How much fuel to leave in tank

I’ve got an 82 gallon tank and whatever is left in the tank after the last trip is what stays in the tank. I just stabilize and close the valves on the fuel tank and forget about it. Even with a ½ tank there is just not enough free space in the tank for condensation to make a difference whatsoever.
 

red10

Petty Officer 2nd Class
Joined
Dec 11, 2003
Messages
175
Re: Winterizing - How much fuel to leave in tank

km2 do a search on non-oxygenated gas in mn, there was a link that had ethanol click on that or msra
 

sangerwaker

Commander
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Jul 29, 2004
Messages
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Re: Winterizing - How much fuel to leave in tank

Here's a link to Minnesota stations that sell non ethanol gas.<br /><br /> web page
 

crazy charlie

Vice Admiral
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May 22, 2003
Messages
5,581
Re: Winterizing - How much fuel to leave in tank

You are way off base with that one Dingbat.A half of a tank is plenty of room for condensation.If thats what you do then you better never forget to change your fuel water seperator or you will get stuck your first time out.Charlie
 

Scaaty

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May 31, 2004
Messages
5,180
Re: Winterizing - How much fuel to leave in tank

JEEEEZZZ...too much rocket science here. When you feel like getting ready to pull it out for the winter, fill it about halfway (or double whats in there with fresh) with enough Stabil to cover whats in there plus what ya add, run around the lake for 10 minutes, do what ya gotta do for winterizing, and tape/plug the damn vent up. Worked for me the last few decades. Gas cans in your shed are sealed, and you don't have them fill up with water do you? And I live in Puget Sound....we do get some drizzle here. And ALWAYS leave room for expansion (thats where the 1/2 tank come into play after taping off the vent). Does it not say that on every gas can made? And on losing octane, its basically the volitile stuff that disappears, and thats what creates the BOOM..gas don't burn, fumes do.
 

cc lancer

Petty Officer 1st Class
Joined
Aug 23, 2004
Messages
371
Re: Winterizing - How much fuel to leave in tank

JEEEEZZZ...too much rocket science here.<br /><br />And the marina owners put $5,000. worth of gas in their above ground tanks to sit for 6 months.
 
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