Winterising - keeping Diesel tank completely full over the winter - good practice or urban myth?

[Ken X]

Funny stuff diesel. We had to light a fire under diesel tanks a few times back in the '80s.  Not seen it done recently so I presume formulations have improved.

 

Had a bit of fun one winter when visiting the outlaws in Kandersteg, Switzerland. We flew out, but the bro-in-law drove his new Mercedes over. 

 

Next morning, it was well below freezing and the lovely new Mercedes refused to start. Dashboard was like a Christmas tree. The locals sniggered a lot and asked him where he last refueled. "France" was the answer. Ah they said. "There's your problem, we have a local formulation here. We would sling some petrol in like we do on the tractors, but it would probably stuff the exotic engine."

 

We helped push it into a barn and left it for a day to warm up. Twas fine after that and a local refuel.  

[PineappleGuy]

Given that there is some uncertainty over what grade you might be filling up with in the autumn, is there any harm in adding something like STA-BIL Diesel Winter to the fuel tank or could it have an adverse effect if you do happen to get winter grade fuel?

[Jen-in-Wellies]

If the weather is so cold that the diesel has waxed, then the boat is also frozen in and not going anywhere. Still might need it for battery charging and perhaps heating too, depending on the mooring and boat. 

[Alan de Enfield]

3 minutes ago, Jen-in-Wellies said:

If the weather is so cold that the diesel has waxed, then the boat is also frozen in and not going anywhere. Still might need it for battery charging and perhaps heating too, depending on the mooring and boat. 

 

Wax crystals start to form in Diesel from +1 degree C to -6 degrees C,

Below that the wax starts to become a 'solid block'.

[ditchcrawler]

Some diesel cars are fitted with heated filter housing now so I would expect lorries to have them

 

Edited March 24 by ditchcrawler

[Mike Coombes]

1 hour ago, Alan de Enfield said:

 

In the UK, caravans are using predominently Butane (blue cylinders), but boats are virtually 100% Propane (Red cylinders)

 

When camping / hiking the gas cylinders are a 'mix' of typically 70% butane and 30% propane as Butane provides 9% more energy per unit of liquid volume than Propane.

 

A fellow Sailing Club member knocked on our hull after a boozy early December Commodores dinner at Gosport some years ago, where those who had to drive stayed on their boats. His blue cylinders were giving no gas. Our orange one was fine.

 

I told him the trick, he and his two sons then pissed on the cylinder in use, it warmed it enough for the gas to shift and they got their morning cuppa.

 

Convesely, had to do the same with overheated motorcycle brake drums once or twice.......................................

[jonathanA]

4 hours ago, Jen-in-Wellies said:

Depends on the country. UK is near 100% propane all year round. Some countries mix in more butane in the summer. Too much butane can interfere with it vaporising in winter. https://www.mylpg.eu/useful/lpg-mixture#mixture

I was talking about calor bulk propane in the UK. No idea what Johnny foreigner does. 

 

I've had to pour a kettle of hot water over the regulator on a bulk tank a few times on early winter frosty mornings. 

[ditchcrawler]

1 hour ago, jonathanA said:

I was talking about calor bulk propane in the UK. No idea what Johnny foreigner does. 

 

I've had to pour a kettle of hot water over the regulator on a bulk tank a few times on early winter frosty mornings. 

But what actually freezes, the mechanism or liquid in the gas? You have to take natural gas down to minus 30 before you will get any liquid condensing out

[Mike Coombes]

6 minutes ago, ditchcrawler said:

But what actually freezes, the mechanism or liquid in the gas? You have to take natural gas down to minus 30 before you will get any liquid condensing out

 

I dont know if ANYTHING freezes, but when filling Calor Propane, it will not flow from the donor to the reciever in cold weather.

 

I hang my donor, wrapped in a black bin liner, in the sun and have the reciever in a container of cold water with a couple of ice packs in it.

 

I doubt I will have to bother again now the yacht is sold-that took 3.9 kg propane and for three years they were almost impossible to get, so I bought the connecting pipe and refilled my own from a 13 kilo bottle.

 

I was VERY careful at first with weighing so I did not exceed their 80% maximum capacity. I soon found that when floating in the iced water, the moment they reached negative bouyancy they were 80% or just under.

[jonathanA]

52 minutes ago, ditchcrawler said:

But what actually freezes, the mechanism or liquid in the gas? You have to take natural gas down to minus 30 before you will get any liquid condensing out

I don't know, i suspect the regulator mechanism, i doubt there is much water vapour in calor gas. What I think happens is expanding gas in the regulator freezes any moisture in the air around and freezes the mechanism.   A good few years ago when running a temporary outdoor kitchen i had a limited number of calor bottles and linked a couple of cookers, water boiler, boiling rings an probably something else into a single regulator on a 19Kg bottle. this was the middle of august (so it was raining !) and one morning none of the gas rings would light. when i went to check the bottle the regulator was in a block of ice... plenty of gas in the bottle just too much off take for the size of bottle/regulator.  

 

propane liquid boils at -44C (google says) 

[ditchcrawler]

2 hours ago, jonathanA said:

propane liquid boils at -44C (google says) 

Yes that is how we use to cool the natural gas to get all the liquid out down to -30 F

[Ex Brummie]

I installed my regulator (propane) with a 't' in the outlet. I take the gas off the branch, and the bottom port is plugged. After a year or so, it is amazing how much sludge collects in the drain I have introduced. This would be going down the internal pipes otherwise.

As regards the diesel tank in the title, anyone who filled up for last winter will now be quids in!

[Ronaldo47]

My understanding is that butane remains a liquid below about +2°C.  If it is only a few degrees above that temperature, gas will be produced, but the act of vaporisation reduces the temperaure of the liquid,  so gas production soon ceases. The gas I use in my gas blowlamp is a butane/propane mixture which does work in cold weather.

 

I well remember the large propane tank that builders were using to heat a large vat of bitumen outside my office, becoming encrusted with ice up to what would have been the  liquid propane level. The tank was standing in the sunshine on a hot day in mid-summer. 

Edited March 24 by Ronaldo47
Typos

[wakey_wake]

 

On 20/10/2025 at 10:10, JoeC said:

A link to an article about fuel. sticky fuel update - CanalsOnline Magazine

The article says they couldn't figure out what was wrong with the fuel, and it wasn't geographical.

 

Then the later post,

On 20/10/2025 at 10:59, Paringa said:

This from the Marine16 website

Winter Lay up, to fuel or not to fuel?

Quote

Modern diesel is highly unstable, it’s been refined to within an inch of it’s life to remove the sulphur and now has min 7% plant oil along with animal and cooking fats.

 

Something comes to mind - around 2021(?) for car MOT, I borrowed the garage's car for the day and it needed fuel. I said I would fill at a specific Tesco as it was on the way and he said "Don't!". He reckoned something was wrong with Tesco's fuel because several customers had problems after using it.

 

It's possible Tesco had a bad batch of fuel? They are often among the cheaper garages around here so I presume they push the suppliers to lower prices. Maybe they found a source of cheap ex-food oil and thought they were being smart and saving us money?

 

This is hearsay and perhaps stale hearsay, but I've never bought any Tesco diesel since... and nothing bad happened except maybe 1p/litre more.

[Momac]

6 hours ago, wakey_wake said:

 

 

It's possible Tesco had a bad batch of fuel? They are often among the cheaper garages around here so I presume they push the suppliers to lower prices. Maybe they found a source of cheap ex-food oil and thought they were being smart and saving us money?

 

Its possible they had a dad  batch eg there was bug in it or water entering their tank or something like that , We shall never know  . I doubt very much that Tesco buy lower standard of fuel or that any such thing  exists. 

Maybe Tesco run their fuel stations at very low margins compared to others as i dare say a good price on fuel attracts customers to the supermarket .

 

A very long time ago I did have  a bad batch of petrol  . Almost took the car in for fault finding then added some fresh petrol and the problem was  solved.

 

I know  of a marina that once had bug in their fuel .

White road diesel is the same thing  as red diesel and it is not immune from diesel bug, 

[Tony Brooks]

7 hours ago, wakey_wake said:

It's possible Tesco had a bad batch of fuel? They are often among the cheaper garages around here so I presume they push the suppliers to lower prices. Maybe they found a source of cheap ex-food oil and thought they were being smart and saving us money?

 

Very unlikely, look at the small print on the delivery tankers are you will see they are owned by the same companies as the major names use. I understand many supermarkets and large commercial fleet operators buy via Mabanaft.

 

It is common for people to promote the supermarket fuel is bad line, but it has to be produced to the required EN standard, exactly the same as the main name forecourts, and remember when a major petrol company produced and marketed a "better" fuel that wrecked customers' engines.

 

Watch and fuel distribution depot and see the variety of branded tankers filling from the same facility.

 

As Momac says Tesco may have been infected with bug in their storage tanks and I know that when someone who knows questions the supermarkets them about what the large pieces of filtering equipment are doing on their forecourt they get very cagey. 

 

 

Edited to add: If you are on any forecourt for diesel and notice a number, but not, all diesel pumps are out of use then be wary, that often meams those pump's filters have blocked, and that tends ot indicate a high bug content in the fuel.

Edited April 17 by Tony Brooks

[Alan de Enfield]

11 minutes ago, Tony Brooks said:

Edited to add: If you are on any forecourt for diesel and notice a number, but not, all diesel pumps are out of use then be wary, that often meams those pump's filters have blocked, and that tends ot indicate a high bug content in the fuel.

 

Currently our local garage has only 1 pump for petrol and 1 pump for diesel, all others are locked-off.

 

He is now 6 days overdue for a delivery and no promises forthcoming about when he will get a delivery.

He has fuel but is trying to ration it to 'locals' by 'looking' as if he is out of stock.

 

Edit - Diesel £1.97/litre

Edited April 17 by Alan de Enfield

[Ronaldo47]

It has been asserted that there is no difference between supermarket and filling station fuel. However, locally at least,  E5 petrol from  Esso and  BP is 99 octane, whereas Asda's E5 is 97 octane. I don't know what Tesco's E5 is.

Edited April 17 by Ronaldo47
Tesco added

[wakey_wake]

4 hours ago, Momac said:

10 hours ago, wakey_wake said:

It's possible Tesco had a bad batch of fuel? They are often among the cheaper garages around here so I presume they push the suppliers to lower prices. Maybe they found a source of cheap ex-food oil and thought they were being smart and saving us money?

Its possible they had a dad  batch eg there was bug in it or water entering their tank or something like that , We shall never know  . I doubt very much that Tesco buy lower standard of fuel or that any such thing  exists. 

My thoughts were on 'sticky fuel' rather than 'diesel bug'. I agree that we shall never know. I also see that I may be irrational in continuing to avoid Tesco.

 

I'm looking to my chemistry knowledge, which was never great and is probably barely above A-level. If an ex-food source of oils has been used then there will be a mixture of chain lengths and double bonds (from unsaturated or poly-unsaturated fats). A wider variety of chemical structures in the blend gives more opportunity for something to get oxidised or react with an additive.

 

I'm also thinking there must be blenders in this supply chain. Dino juice comes in, assorted 'bio' stuff comes in, somebody mixes them together, there are distribution centres which must hold stocks in a variety of tanks, and a transport company brings it to the petrol stations. All of this is opaque to me but the information we have points to each step existing somewhere.

 

The question then arises, when placing an order to supply a network of petrol stations, can a large enough owner influence the blending recipe used for their deliveries? Tesco seems to be of that size, and is at least rumoured to strong-arm suppliers.

 

3 hours ago, Tony Brooks said:

It is common for people to promote the supermarket fuel is bad line, but it has to be produced to the required EN standard, exactly the same as the main name forecourts, and remember when a major petrol company produced and marketed a "better" fuel that wrecked customers' engines.

 

My understanding is that the standard is a target. The blending recipe is a means of achieving that target, and I guess it is trade secret with some commonly known aspects.

 

If a major petrol company can end up accidentally running dodgy experiments with their blending recipe and paying out damages (?) then I see that as supporting the 'bad batch' hypothesis. Question then becomes "how soon would they notice their recipe was bad, and would any outsiders ever hear about it?" and given the damage bad fuel can do, the incentive to keep it quiet looks quite strong.

 

3 hours ago, Tony Brooks said:

Watch and fuel distribution depot and see the variety of branded tankers filling from the same facility.

 

Same facility, yes. Same source tank for a tanker with a specific destination? You can't tell from the outside.

 

The depot must have multiple tanks because they couldn't operate with just one large one. They could never take it offline for service.

Therefore they have several tanks and operate them in rotation, and therefore they are capable in theory of supplying different blends to different customers, per tanker lorry compartment.

[Tony Brooks]

4 minutes ago, wakey_wake said:

My thoughts were on 'sticky fuel' rather than 'diesel bug'. I agree that we shall never know. I also see that I may be irrational in continuing to avoid Tesco.

 

I'm looking to my chemistry knowledge, which was never great and is probably barely above A-level. If an ex-food source of oils has been used then there will be a mixture of chain lengths and double bonds (from unsaturated or poly-unsaturated fats). A wider variety of chemical structures in the blend gives more opportunity for something to get oxidised or react with an additive.

 

I'm also thinking there must be blenders in this supply chain. Dino juice comes in, assorted 'bio' stuff comes in, somebody mixes them together, there are distribution centres which must hold stocks in a variety of tanks, and a transport company brings it to the petrol stations. All of this is opaque to me but the information we have points to each step existing somewhere.

 

The question then arises, when placing an order to supply a network of petrol stations, can a large enough owner influence the blending recipe used for their deliveries? Tesco seems to be of that size, and is at least rumoured to strong-arm suppliers.

 

 

My understanding is that the standard is a target. The blending recipe is a means of achieving that target, and I guess it is trade secret with some commonly known aspects.

 

If a major petrol company can end up accidentally running dodgy experiments with their blending recipe and paying out damages (?) then I see that as supporting the 'bad batch' hypothesis. Question then becomes "how soon would they notice their recipe was bad, and would any outsiders ever hear about it?" and given the damage bad fuel can do, the incentive to keep it quiet looks quite strong.

 

 

Same facility, yes. Same source tank for a tanker with a specific destination? You can't tell from the outside.

 

The depot must have multiple tanks because they couldn't operate with just one large one. They could never take it offline for service.

Therefore they have several tanks and operate them in rotation, and therefore they are capable in theory of supplying different blends to different customers, per tanker lorry compartment.

 

I understood that any company specific additives were added at the tanker filling stage and until then the fuel was more or less the same.

 

Remember that the fats and oils used to produce bio-diesel are subject to chemical processing, that includes (I think) caustic soda and then "washing", so I doubt its composition would be the same as the raw fats and oils. 

 

 

[Llamedos]

As the OP of this thread I see that it is still going...

 

Probably off topic now for the current conversation, but just to feedback, I did indeed leave the tank half empty over the winter dosing it first with Marine 16 complete.

 

When opening up the boat a month or so ago I tested it with some water detection paste and found zero water in the bottom of the tank. The engine started first go too.

 

The only disadvantage for me has been that the price of diesel has now doubled so filling the tank in the autumn would have saved me a few bob! 

Edited April 17 by Llamedos

[wakey_wake]

1 hour ago, Tony Brooks said:

Remember that the fats and oils used to produce bio-diesel are subject to chemical processing, that includes (I think) caustic soda and then "washing", so I doubt its composition would be the same as the raw fats and oils. 

Yes I know they're not just chucking some used deep-frying oil into the mix and sending HMRC a fiver.

The hydrolysis and washing processes will probably depend on the composition of what goes in, and they will have tools for checking that.

Still there is clearly room for error, and error may cause damage disproportionate to the action or any costs saved, and part of the function of a legal department is to try to shift those costs to someone else. 😞

[Peanut]

Tanker drivers are well paid, and distribution costs are not insignificant. Far better to fill your fuel stations from the nearest refinery, and keep your delivery cost down. There is no point in sending your tankers all over the country.

[cuthound]

On 17/04/2026 at 11:16, Ronaldo47 said:

It has been asserted that there is no difference between supermarket and filling station fuel. However, locally at least,  E5 petrol from  Esso and  BP is 99 octane, whereas Asda's E5 is 97 octane. I don't know what Tesco's E5 is.

. Tesco's E5 is 99 RON. I use it in one of my cars.

 

Recently Tesco's had run out, so I used Sainsbury's 97 RON on a long journey I do about once a month and got 3 mpg less.

 

 

23 hours ago, wakey_wake said:

My thoughts were on 'sticky fuel' rather than 'diesel bug'. I agree that we shall never know. I also see that I may be irrational in continuing to avoid Tesco.

 

I'm looking to my chemistry knowledge, which was never great and is probably barely above A-level. If an ex-food source of oils has been used then there will be a mixture of chain lengths and double bonds (from unsaturated or poly-unsaturated fats). A wider variety of chemical structures in the blend gives more opportunity for something to get oxidised or react with an additive.

 

I'm also thinking there must be blenders in this supply chain. Dino juice comes in, assorted 'bio' stuff comes in, somebody mixes them together, there are distribution centres which must hold stocks in a variety of tanks, and a transport company brings it to the petrol stations. All of this is opaque to me but the information we have points to each step existing somewhere.

 

The question then arises, when placing an order to supply a network of petrol stations, can a large enough owner influence the blending recipe used for their deliveries? Tesco seems to be of that size, and is at least rumoured to strong-arm suppliers.

 

 

My understanding is that the standard is a target. The blending recipe is a means of achieving that target, and I guess it is trade secret with some commonly known aspects.

 

If a major petrol company can end up accidentally running dodgy experiments with their blending recipe and paying out damages (?) then I see that as supporting the 'bad batch' hypothesis. Question then becomes "how soon would they notice their recipe was bad, and would any outsiders ever hear about it?" and given the damage bad fuel can do, the incentive to keep it quiet looks quite strong.

 

 

Same facility, yes. Same source tank for a tanker with a specific destination? You can't tell from the outside.

 

The depot must have multiple tanks because they couldn't operate with just one large one. They could never take it offline for service.

Therefore they have several tanks and operate them in rotation, and therefore they are capable in theory of supplying different blends to different customers, per tanker lorry compartment.

 

I live very close to Kingsbury Fuel Depot, where as Tony says you used to be able to see tankers from the various companies queueing up at the same bulk tank. Nowadays most fuel is distributed by  Hoyer. The tanks store two fuels, diesel and petrol.

 

The super fuels are obtained by an additive, which is added to the tankers before the standard fuel is added 

 

The additives are brand specific.

Edited April 18 by cuthound
Spillung

[Momac]

12 hours ago, cuthound said:

. Tesco's E5 is 99 RON. I use it in one of my cars.

 

Recently Tesco's had run out, so I used Sainsbury's 97 RON on a long journey I do about once a month and got 3 mpg less.

 

I tried the premium e5 petrol in my 2019 plate Mercedes and it made no difference to fuel economy. But I use it in my lawnmower and that starts easier and runs better on e5.