Winterising diesel fuel tank

FairweatherDave

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I have read several threads on the subject and I'm still stuck on the fence.
My tank has about 15litres remaining (60litres when full). It is a stainless tank with a small filler cap but a good tap underneath to drain off fuel or water. My fuel is treated with bug killer (M16?). No problems.
Option one is run off a sample from bottom tap and assuming it is clean (maybe a little water) fill the tank to the brim and treat the diesel. Next time the engine gets a run is April and even then won't need a refill/top up until maybe June or July.
Option two is drain the tank and use the clean fuel in the car. Then "clean" the tank. Fill tank in April. I'm not sure how best to clean the tank with such a small opening.
Option one is the easy option and I have never had any bug issues but always aware it could happen and modern fuel scare ? stories..... Apologies if this is a repeat debate but I haven't located the answer from googling.
(BTW I'm talking using road fuel from normal garages in the uk, not marinas, and it is a sailing boat not motor)
Grateful if someone can push me off the fence :)
 
I left my boat in Greece in July 2019 with the stainless steel tank about 3/4 full of diesel. It has never had any water in it thanks to good filler cap sealing, sensible filler location on top of the coaming and usual care. It has never had any bug treatment.

I returned in September 2022. I sampled the tank with my Pela, found no sludge or water and started the engine. It ran perfectly, consuming the tank contents over a long delivery trip.
 
Thanks Vyv. I think if the fuel I top up with now is the same as that sold in 2019 I would have no hesitation in continuing with my normal practice of brim full overwinter. And using a modern additive. I am curious about cleaning a tank and do have the opportunity as it is pretty empty at the moment - but worried I would not really make any impact/could introduce problems and I do have enough other maintenance to do (standby on replacing PSS seals :))
 
I suggest - Leave it alone ......

My 70ltr tank gets left every winter partially filled ... and our winters can drop to -30C or lower.

During sail season - I dose the fuel to cover any bug issues ..... and that's it. Even though its Summer Grade Diesel with a rating of -7C CFPP ...... I don't bother to add CFPP additive .... as I'm not going to run the engine in such low temps. By time spring comes - the diesel is back in warmer temps.
I have only drained the tank 2x since she came here in 2007 ..... both due to bad fuel picked up during summer cruises. Drained - dosed - settled - put back the clean fuel with extra dose.
 
Would it not be worthwhile to take the opportunity to improve tank access as a safeguard against future problems? There have been a number of past threads on the best way to install a suitable aperture, that would give you peace of mind.
 
Would it not be worthwhile to take the opportunity to improve tank access as a safeguard against future problems? There have been a number of past threads on the best way to install a suitable aperture, that would give you peace of mind.
Hmmmm. I shall read up - fair point - instinctively more inclined to easy option one though.
 
I left my boat in Greece in July 2019 with the stainless steel tank about 3/4 full of diesel. It has never had any water in it thanks to good filler cap sealing, sensible filler location on top of the coaming and usual care. It has never had any bug treatment.

I returned in September 2022. I sampled the tank with my Pela, found no sludge or water and started the engine. It ran perfectly, consuming the tank contents over a long delivery trip.
Just wondering . Was the diesel bio or non bio diesel ?

From the bio petrol perspective, I have experienced problems and I now put what's left into the car at the end of the season and clear all the tanks. There is a fairly straightforward test to determine if you have bio in your fuel.
 
Just wondering . Was the diesel bio or non bio diesel ?

From the bio petrol perspective, I have experienced problems and I now put what's left into the car at the end of the season and clear all the tanks. There is a fairly straightforward test to determine if you have bio in your fuel.
It had the potential to have 5% FAME in it but I have no idea if it did.
Coincidentally today I have been working on a petrol fuelled car that has stood for some time, less than a year with me but some time longer before that. On taking the top off the carburettor I could barely recognise the fluid in there as petrol. Very yellow and murky and almost without smell.
 
if its only 15 litres and you have a good drain tap, I would drain it out into sealed containers and leave the tank dry. when you are ready to restart boating you can open the containers check the fuel for problems and refill your main tank
 
Just wondering . Was the diesel bio or non bio diesel ?

From the bio petrol perspective, I have experienced problems and I now put what's left into the car at the end of the season and clear all the tanks. There is a fairly straightforward test to determine if you have bio in your fuel.

Please enlighten us with your 'fairly straightforward test' .... I'm intrigued ..... being in the 'business'.

Given that there are very few light to medium distillate fuels left that do not have Bio content .... I am again intrigued.

As to diesel ....... interested to know where you would obtain any without Bio addition ...
 
Please enlighten us with your 'fairly straightforward test' .... I'm intrigued ..... being in the 'business'.

Given that there are very few light to medium distillate fuels left that do not have Bio content .... I am again intrigued.

As to diesel ....... interested to know where you would obtain any without Bio addition ...
My diesel supplier also supplies several of Calmac's fleet of West Coast of Scotland car ferries. I am led to believe that after experimenting with low sulfur bio diesel, Calmac demanded a return to non bio, high sulfur fuel. I get what they get.
 
Please enlighten us with your 'fairly straightforward test' .... I'm intrigued ..... being in the 'business'.

Given that there are very few light to medium distillate fuels left that do not have Bio content .... I am again intrigued.

As to diesel ....... interested to know where you would obtain any without Bio addition ...


Please enlighten us with your 'fairly straightforward test' .... I'm intrigued ..... being in the 'business'.

Given that there are very few light to medium distillate fuels left that do not have Bio content .... I am again intrigued.

As to diesel ....... interested to know where you would obtain any without Bio addition ...
I was more interested in removing ethanol for longer storage . It would seem that fuel additives can help with older fuel but they have no effect on removing ethanol.

I attach a Youtube which probably explains it better than I can . You don't have to buy a kit if you have some clear measuring jars/beakers. The downside in draining off ethanol is the remainder of the fuel is likely to be of a much lower octane . As you are in the business it would be interesting to know if this is significant.
 
It had the potential to have 5% FAME in it but I have no idea if it did.
Coincidentally today I have been working on a petrol fuelled car that has stood for some time, less than a year with me but some time longer before that. On taking the top off the carburettor I could barely recognise the fluid in there as petrol. Very yellow and murky and almost without smell.
Thanks Vyv.

You might be interested in the Project Farm Youtube. I'm a fan of his and he has no links to any suppliers. I didn't
realize that E85 fuel existed . He has an example of the effect it had on a carburetor.

 
I have had a litre of diesel sat on a shelf for over a year in an open container. Todate no water in the bottom of the container.
 
My diesel supplier also supplies several of Calmac's fleet of West Coast of Scotland car ferries. I am led to believe that after experimenting with low sulfur bio diesel, Calmac demanded a return to non bio, high sulfur fuel. I get what they get.
CalMac get the same cherry everyone else gets, which means it's ULSD and must contain a quantity of FAME as per the RTFO rules.
 
if its only 15 litres and you have a good drain tap, I would drain it out into sealed containers and leave the tank dry. when you are ready to restart boating you can open the containers check the fuel for problems and refill your main tank
I quite like the sound of this. But if I drain the tank will it be "dry" or will any residue be the ultimate breeding ground for bug? Not a rhetorical question, I don't know.
 
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