Old diesel fuel

Feb 6, 2013
437
Hunter 31 Deale, MD
How long can treated diesel fuel be trusted? Most of the 15 gallons in the tank is from 2012 and was treated. Unless I can be convinced otherwise, I think it needs to be replaced before the engine is started later this month.

Thanks.
 
Sep 15, 2009
6,243
S2 9.2a Fairhope Al
How long can treated diesel fuel be trusted? Most of the 15 gallons in the tank is from 2012 and was treated. Unless I can be convinced otherwise, I think it needs to be replaced before the engine is started later this month.

Thanks.
i would do the same thing ......save the old fuel and find some one who heats with oil and give it to them to heat with ...that way you get fresh fuel and some one gets to stay warm .....that way everybody wins......

regards

woody
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
How long can treated diesel fuel be trusted? Most of the 15 gallons in the tank is from 2012 and was treated. Unless I can be convinced otherwise, I think it needs to be replaced before the engine is started later this month.

Thanks.
drain some in a jar... if it looks a bit cloudy, remove it.... if its clear, burn it in the motor.

as diesel fuel ages, it get cloudy... in the cool atmosphere of the fuel tank, depending on how much fuel was in the tank as it sat there, will determine how much water it has absorbed and caused it to degrade....
clear fuel is good fuel....
but keep in mind, even if the fuel is good, there could be some water setting in the bottom of the tank that will cause problems.

if you can get to the tank and remove the fuel sender, you should be able to list the boat enough to get the water to a corner so you can reach it with a pump thru the gauge hole....
 
Jan 2, 2013
3
Coronado 35 center cockpit Bayfield, WI
fuel age

You might be surprised. I work for a guy who collects old motor coaches. I've seen him buy a coach that has been sitting for over 25 years, put in fresh batteries, and fire up the engine with the fuel that was put in before the bus went out of service. The engine ran normally on the old fuel. I don't know that I would recommend this for your boat, but diesel is much more stable than gasoline.
 
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
You might be surprised. I work for a guy who collects old motor coaches. I've seen him buy a coach that has been sitting for over 25 years, put in fresh batteries, and fire up the engine with the fuel that was put in before the bus went out of service. The engine ran normally on the old fuel. I don't know that I would recommend this for your boat, but diesel is much more stable than gasoline.
agree...
as long as its kept out of the sun, in a cool place.... and air/moisture is not allowed to freely get to it.
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Most of the 15 gallons in the tank is from 2012 and was treated.
Here is a recent report on diesel fuel taken from an 5,000 liter underground fuel tank which supplies a standby generator. The tank was last filled in 2008. The tank shows no water and only has an atmospheric vent so air movement is minimal.

I must admit, I was surprised as well but the lab assured me this is the norm if the fuel is stored cool, dry, and has no air movement.
 

Attachments

Mar 19, 2010
30
Hunter 1997 376 Ventura, CA
I had my fuel tank sitting for a couple of years. So I had the fuel polished and it works fine no water or algae.
Get the fuel polished or set up a way to polish it with your own system.
Cheers Gary
 
Jun 23, 2013
54
hunter 33.5 tampa
Re-bought my old boat back, had been on the dock for 2 or more years. Topped off the fuel with only a few gallons and took it on a 3 day trip, motor sailed with no problems.
It did have a new racor filter which still looks good today.
 
Apr 8, 2014
4
Hunter 40.5 Legend Hampton
Just installed a second Racor 500, with selector switch between the filters, a vacuum gauge at the helm, and a recirculating pump. 20 year old boat, so there will be crud, and it will be defeated.
 
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
Guys that depend on their life for the quality of the fuel, small singe engine airplanes, usually take a fuel sample before they take off to check it. Stick a short length of plastic pipe or hose in the tank to the bottom, put your thumb over the top, pull it out and release it into a mason jar. Let it sit until it settles then look at it. Just an idea, hope it works. People are running diesels on old used French fry oil and stuff so they are pretty robust as long as the fuel is clean. I gave some old fuel to a guy that ran a diesel power scuba charter boat as the 20 gallons would be burned up in very short time. He polished it going into his tank and used 5 gallons at a time. At over 4 bucks a gallon he was happy to have the fuel and it was so diluted with fresh fuel it wasn't an issue. Truckers would also be happy to have it.
 
Sep 26, 2008
566
- - Noank CT.
How long can treated diesel fuel be trusted? Most of the 15 gallons in the tank is from 2012 and was treated. Unless I can be convinced otherwise, I think it needs to be replaced before the engine is started later this month.

Thanks.
Here is just another opinion but unless fuel is contaminated (as others have suggested take a sample) treated fuel from 2012 will be OK. Diesel has a very long "shelf life" if not contaminated by other sources. If you want to error on side of caution get it polished as others have suggested. Myself personally if sample looks OK would not worry about it. I would however change filters after it is used (something that should be done regardless only because if the fuel is that old presumable the filters are at least the same age if not older ? ?). May want to check or change filters before using the fuel anyway. I have personal used treated fuel that was four years old and with no problems. Maybe more important is do you expect to use it all shortly or will you be keeping it for a extended time ?
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
The definitive unsophisticated 'field' test for #2 diesel oil is to put a small amount into a clear container, hold that filled container between your eyeballs and STRONG white light. If there is any 'haze' caused by that white light (Tyndall effect) it denotes gross contamination by particles larger than ~2 to 15µM.
The goal of such filtration by Racors, etc. is only to remove 0.05% (by weight) of the particles in the fluid, any more than that the filters will rapidly choke. If you have a noticeable haze in strongly backlighted fuel youre most probably above that 0,05% range.

If haze, dont put it in your tank or remove it, and put it in your home oil burner tank.
 
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Dec 29, 2008
805
Treworgy 65' LOA Custom Steel Pilothouse Staysail Ketch St. Croix, Virgin Islands
Clean fuel still works

I am by no means an expert in fuel. However, for perspective, we carry as much as 500 gallons of diesel in 3 tanks. We haven't purchased fuel since 2003 until this fall. My understanding is that diesel does lose cetane rating over time, but I can tell you that we had no trouble burning this old fuel for 11 years. Just the same, we did decide to have the last 125 gallons removed this fall, cleaned the tanks, and purchased 337 gallons of new fuel. We also installed a new FilterBOSS system at the same time. There is a lot of good advice above regarding treating and polishing. My experience is that the age of your fuel us the least if your worries. The condition of the fuel is much more important than its age.
 

Jampit

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Apr 22, 2015
6
Beneteau 311 Killyleagh
I have an Oceanis 311 and unfortunately some water HAS got into the diesel. I am wondering how to drain off the contaminated fuel. The tank is under the floor of the cockpit can only be reached- with difficullty- from the aft cabin. It is impossible to get a syphon down the inlet pipe as it has a 90 degree bend in it. The normal feed to the engine has a vertical lift - presumably the end of this is off the bottom- and hence above any water! Is there any other way of accessing the tank to drain it completely and get rid of the water?
 
Apr 8, 2014
4
Hunter 40.5 Legend Hampton
Pump the fuel

I have an Oceanis 311 and unfortunately some water HAS got into the diesel. I am wondering how to drain off the contaminated fuel. The tank is under the floor of the cockpit can only be reached- with difficullty- from the aft cabin. It is impossible to get a syphon down the inlet pipe as it has a 90 degree bend in it. The normal feed to the engine has a vertical lift - presumably the end of this is off the bottom- and hence above any water! Is there any other way of accessing the tank to drain it completely and get rid of the water?
I bought a diesel fuel pump at Advance Auto for recirculating old fuel. You could use one of those to pump the tank dry, pulling the old diesel through your filter. Easier than getting to a buried tank. Pump into some 5 gallon cans, and clean the filter when finished. When finished, plumb the pump in more permanently for polishing anytime.
 

DougM

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Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
I have an Oceanis 311 and unfortunately some water HAS got into the diesel. I am wondering how to drain off the contaminated fuel. The tank is under the floor of the cockpit can only be reached- with difficullty- from the aft cabin. It is impossible to get a syphon down the inlet pipe as it has a 90 degree bend in it. The normal feed to the engine has a vertical lift - presumably the end of this is off the bottom- and hence above any water! Is there any other way of accessing the tank to drain it completely and get rid of the water?
I had the same situation with my 323. I disconnected the fuel line at the Racor and used a cheapie oil change pump to transfer the fuel to a five gallon container. The fuel still looked good but had been only partially used over five years. The guys in the marina shop use an oil heater, so I was able to give to them.