Empty gas tank or leave full?

R

rhodyboater

New Member
Feb 25, 2009
212
Rhode Island
Boat Info
340 Sundancer 2004
Engines
Twin 8.1 mercs
Sorry for asking a question that has probably been answered many times but I couldn't get any hits on the search feature.
Anyway, I used to leave my gas tank full for the winter, on the theory that a full tank will eliminate water vapor from forming, to ward off ethanol problems, and never had any problem.
This year I bought a boat with a much bigger gas tank (225 gals) and it will cost a bundle to fill that baby up. Plus, if there's any chance of the whole tank going "stale", I wouldn't want to take that chance with $1000 worth of gas.
So...what's the latest advice?
Thanks.
 
I asked the same question this what I concluded... Fill it up... Less moisture in a full tank, and typically the gas prices are lower in the fall.... I did not fill up last year and regretted it... I am watching the gas prices by me drop and plan to fill my girl up in late Oct...
 
Have to say filler up. Use stable to store your fuel, and enjoy next spring as prices go back up and you have a full tank...

Jason
 
I fill both tanks up and add Startron. No ethenol fuel only. IF I could'nt find no ethenol gas I would leave them almost empty with some startron and fill them up in the spring.... Is it spring yet?????
 
You can make an argument for both sides - full or empty. The "fill-up" side is to keep moisture/condensation from forming in the tank. "Empty" proponents say if the gas goes bad, you don't have much bad gas to contend with. I've always topped off, for the past 5 years (since we've been stuck with e-10). Never had a problem so that's what I'm doing again this year.

You can't find anywhere in this part of the NE that doesn't have ethanol.
 
Play gas futures. Has worked the past 4 years for me. ie: gas was more expensive in the spring than the fall, so topping off in October has paid off.
 
Im with you on the GRAND but it is better to do it in the fall then wait till its ten prices again... eeerrrrhhhhh.....:smt013

Jason
 
1000 bucks for fuel that you are going to burn the following year isint as bad as having the tank pumped and filtered out because you have water in the fuel come spring time if you dont fillem up
 
Full with stabilizer. No problems with ethanol. It's also a nice bonus cruising in early April around here without having to worry if the gas pumps are open yet.
 
Oh yeah, STARTRON, STARTRON, STARTRON. I started using this product when e10 was rammed down our throats around 2006/7. Ever since, I have added the prescribed dosage each and every time that I take on fuel. Thus far, I have had no issues what-so-ever. Apparently it helps prevent phase separation, which turns 89 octane into 84 octane over time. Tanking up with a higher octane and adding the proper amount of Startron has been a good formula and has kept my old tub running perfectly.
 
First year with this boat - my old boat I could pump all the gas out easily.
Looks like with the Sundeck, the tank wont be completely empty - I don't see an easy way to pump it out.

I've usually been in the "empty tank" camp, and in fact drove around at a very fast and inefficient speeds to burn up as much as possible just before hauling (it felt naughty good - lol)

Right now there's about 5 gallons in it (45 gallon tank).
Would that be considered empty enough?
After reading this thread, I might just fill it up.
But if I decide to stay in the "empty tank camp", is 5 gal in the tank close enough to be considered empty?
 
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I have fulled up the the last 10 years, works good so far.
 
Just topped off today. Keep all your receipts and a log of how much you put in, divide by total engine hours and figure out how much you average in GPH. This season it was 17.07gph. (I know, who cares?!)
 
Does anybody have thoughts on this theory?

My tank was half full when I bought it last spring. No way to know if it had ethanol or Stabil in it. It was nice to have plenty of space to put in fresh gas at the start of the season. I did change out the 5 year old water separating fuel filter before heading out. The engine started and ran fine.

Strangely, living on the western edge of the corn-belt, I do have the option of avoiding ethanol at almost any station. Ethanol fuel is a lot less expensive here, but since my Mercruiser manual clearly isn't too keen on ethanol fuel, especially during winter storage, I've avoided ethanol since mid-summer to burn it all out.

My current thinking is to leave the tank half full, and add Stabil. I'll have room in spring to top off with fresh fuel.

Am I crazy?
 
The only time I have had problems is when I store with an empty or half full tank. Even having added stabil to the gas and running it before I siphoned the gas out. Condensation forms in the air space when there is repeated hot and cold during storage. I have not had any problems ever when storing with a full tank.
 
Tony, did you want that $1000.00 in twenty's or hundreds, I can make either with the profits of the stock market.
 
It's 4.10/gal where I fill up. x 225gals = $922 so I don't need that much after all....lol
I am starting to wonder though...do they make locking gas caps for boats??
I'd hate to find my gas siphoned off in the spring!
 
I'd hate to find my gas siphoned off in the spring!
Click to expand...

Search around this site - it has happened and this question has come up. There is some product out there - not sure hot it works.
 
OK Kids..I am a believer in dont pay forward with at "Best "45 day **** gas.....haul and store boat with whatever is in tank..Startron 3 X whats in tanks....in spring fill up and 2 x startron ..NEVER a Problem...change fuel filtersc2 x annually..$ in the stored boat/gas tanks it a waste of $$$$ IMHO...Best to all.. Lets shoot d sh t in d spring on what we did//BTW have done this since 2000
 
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