How long does diesel last for in the tank?

[tomandsophie]

Because we only run the engine once a week or sometimes once a fortnight just to move the boat to a new mooring (solar panels do all our power and water), I have got a tank full of around 400 litres of diesel that has been there around a year. Does diesel degrade over time? Should I use it all up and then only fill a little at a time rather than constantly topping it up and thus ending up with diesel that will eventually be many years old? Thus far I have kept it topped right up every few months to avoid any condensation, but is this really necessary?

[Alec Gatherer]

My stalled project (sale agreed) has the red diesel that I put in when we arrived at the moorings 4+ yrs ago. The Lister still cracks up instantly and runs & idles on it. Mind you, that's one reason I chose a Lister.

I have not found diesel to deteriorate with time, unlike the new petrol.

Spent all yesterday pumping out the tank on a Riley using the manual lever on the lift pump, so that I can put new (i.e. under a month old) petrol in to start it. 10 gallons! Couldn't have had just a gallon or so could it, oh no.

[WJM]

Someone else may have another angle on this but;

 

As I understand it, the biggest enemy is water in the diesel, which gets in as condensation. The best protection against this problem is to keep the tank as full as possible all the time.

 

My guess is that condensation is the problem you need to focus on rather than the oil 'going off' in some way.

Edited March 14, 2008 by WJM

[blackrose]

Someone else may have another angle on this but;

 

As I understand it, the biggest enemy is water in the diesel, which gets in as condensation. The best protection against this problem is to keep the tank as full as possible all the time.

 

My guess is that condensation is the problem you need to focus on rather than the oil 'going off' in some way.

 

Agreed. The most likely cause of your fuel becoming contaminated is water in the tank leading to a growth of colonies of bacteria. They live at the interface of the diesel/water and metabolise aerobically using the oxygen in the water and the diesel (hydrocarbon) for their energy requirements. These bacterial colonies along with their by-products manifest themselves as a slimy black gunk that can lead to blocked filters and injectors.

 

Keep the tank topped up and you will minimise the potential for condensation inside the tank and the conditions necessary for bacterial growth. In addition many people use fuel additives which are meant to kill the bugs and emulsify any water into the diesel (I've heard some say it disperses the water but I can't understand whre it would be dispersed to inside a sealed tank?)

 

I use Fuelset but I've heard there are some better additives.

Edited March 14, 2008 by blackrose

[Keeping Up]

And do additives like Fuelset go off with time? I use a little bit of a similar product every time I fill the tank, and once again at the end of the winter, but I'm still only half-way through the bottle that I got nearly 20 years ago (it was called "Enersol" or "Enersolve" or something like that, the label has been lost many years ago)

[Timleech]

Keep the tank topped up and you will minimise the potential for condensation inside the tank and the conditions necessary for bacterial growth. In addition many people use fuel additives which are meant to kill the bugs and emulsify any water into the diesel (I've heard some say it disperses the water but I can't understand whre it would be dispersed to inside a sealed tank?)

 

The water gets dispersed within the diesel, ie the additive enables the water and oil to mix. Methylated spirit will do that part of the job, or so it is said. Makes sense, as it is miscible with water and oils.

 

Tim

[andywatson]

Because we only run the engine once a week or sometimes once a fortnight just to move the boat to a new mooring (solar panels do all our power and water), I have got a tank full of around 400 litres of diesel that has been there around a year. Does diesel degrade over time? Should I use it all up and then only fill a little at a time rather than constantly topping it up and thus ending up with diesel that will eventually be many years old? Thus far I have kept it topped right up every few months to avoid any condensation, but is this really necessary?

 

In the 80's I worked as a petroleum engineer on rigs drillling in the desert interior of Oman.

Some of the oil there came straight out of the ground and was only filtered before being usable in the (Cat ) diesel engines of the rig.

That stuff was certainly more than a couple of years old.................

 

As an aside:

At some locations in the south of the country we were were only about 50 miles inland from the Indian ocean.

The local fishermen came to the rigs with barrels of live lobsters which we swapped for barrels of diesel.

Eventually I got sick of eating lobsters with every meal.

I was gagging for a bacon sandwich!

[blackrose]

The water gets dispersed within the diesel, ie the additive enables the water and oil to mix. Methylated spirit will do that part of the job, or so it is said. Makes sense, as it is miscible with water and oils.Tim

In that case it's emulsified as I originally said.

 

And do additives like Fuelset go off with time? I use a little bit of a similar product every time I fill the tank, and once again at the end of the winter, but I'm still only half-way through the bottle that I got nearly 20 years ago (it was called "Enersol" or "Enersolve" or something like that, the label has been lost many years ago)

I don't know, I'll check to see if there's a "use by" date on the bottle I have on the boat this evening. Edited March 14, 2008 by blackrose

[Robbo]

Note, that if you use Biodiesel it will go off after about 3 months. I'll see if I can dig up my source.

[blackrose]

Fuelset doesn't seem to have any expiry date.

[Timleech]

In that case it's emulsified as I originally said.

 

They obviously mean that it's dispersed from its natural settling place at the bottom of the tank.

If that's technically forming an emulsion, fair enough.

 

Tim

[Keeping Up]

Fuelset doesn't seem to have any expiry date.

Thank you.

 

If I get sick after drinking some, I'll know who to blame.

[Nickhlx]

Talking about fuels "going off", I heard the other week that with unleaded petrol, e.g. Shell Optimax or BP Excellium etc, that these fuels do NOT go off, like regular unleaded does after a month.. this from a Shell engineer ... so I have started using it in machines that get used infrequently or intermittently.. like lawnmowers and generator sets...I still would drain the float chamber by switching the petrol tap off (if it has one) and running until it stopped though, as it can still evaporate out of the float chamber leaving residues.

 

Nick

[blackrose]

Talking about fuels "going off", I heard the other week that with unleaded petrol, e.g. Shell Optimax or BP Excellium etc, that these fuels do NOT go off, like regular unleaded does after a month.. this from a Shell engineer ... so I have started using it in machines that get used infrequently or intermittently.. like lawnmowers and generator sets...I still would drain the float chamber by switching the petrol tap off (if it has one) and running until it stopped though, as it can still evaporate out of the float chamber leaving residues.

 

Nick

 

Does regular unleaded really 'go off' after a month?

 

I thought the only difference between regular and super was the octane rating?

[Alec Gatherer]

Does regular unleaded really 'go off' after a month?

 

I thought the only difference between regular and super was the octane rating?

Too right it does. With my stable of elderly cars with varying degrees of age decay I need to be mindful of the length of time that the petrol has been in the tank.

And on many occasions I have cured a customer's non-starting problem by draining off the old fuel and refilling with new. This after leaving the vehicle standing over the winter months.

A little tip - can also be handy if there has been an accidental use of the wrong fuel (i.e. fill with petrol in a diesel vehicle or vice versa). Carburettor engines only.

I have a one-gallon fuel can which I have fitted with a 5/16" spigot fuel take-off near the bottom.

To pump out a tankful of fuel on a vehicle with a mechanical pump, disconnect the fuel feed downstream of the pump and bodge the feed from the portable tank into this, positioning the small tank so that the fuel syphons into the carb (stand on the roof maybe?).

Then bodge a tube from the now-vacant downstream outlet into a suitable drain-off container.

Start the motor; the engine is now running on correct fuel supplied from the small tank, but the mechanical pump is churning out the contents of the fuel tank.

Saved a few of my mates a good few bob has that. Never needed it myself of course, oh no, I just had an hour to spare one day so I thought I'd make the tank. To help my mates out.

[blackrose]

Too right it does. With my stable of elderly cars with varying degrees of age decay I need to be mindful of the length of time that the petrol has been in the tank.

And on many occasions I have cured a customer's non-starting problem by draining off the old fuel and refilling with new. This after leaving the vehicle standing over the winter months.

 

I've never had any problems using regular unleaded petrol that's been stored for months if not years.

Edited March 15, 2008 by blackrose

[Travis]

I seem to remember starting my dads Suffolk Punch every spring after leaving it stood from the end of the previous summer? Never changed the petrol, even the half gallon in the gallon refilling can that never seemed to run out.

 

Or was I learning the benefits of alcohol consumption just about the same time?

 

Andy.

[dave moore]

Hi all

I've never had a problem with any age of diesel and luckily have yet to encounter "Diesel bug".

I'm familiar, however, with the problem of stale/old unleaded petrol. My boat has a 1940 Kelvin J3 which was configured to start on petrol and then switch to diesel. The logic was that in a fishing boat (the original application for many of these engines)with no electrics, the petrol arrangement allowed an easy, low compression start, not unkike swinging over a car with a starting handle.

I found that starting was easy with fresh petrol, but after 2 or 3 weeks the engine was reluctant to fire up. Several years ago I was in conversation with a chap at Audlem who turned out to be one of the Gardener family (engine manufacturers). I mentioned this to him and he cofirmed the relatively short shelf life of unleaded petrol, adding that the Kelvins were designed to start on petrol of a much higher octane rating, such as the old 4star from my earlier motoring days.

I sourced some and found starting to be immediately easier. I continued to use 4 star (still available from a limited number of garages and mainly used, I think, in the vintage car market) until a magneto problem forced a change to glow plug, diesel vapour starting, which I prefer from a safety viewpoint....but it would be nice to be able to repair the magneto one day and have the option of both starting systems!

Cheers

Dave Moore

Edited March 15, 2008 by dave moore

[Hairy-Neil]

....but it would be nice to be able to repair the magneto one day and have the option of both starting systems!

Cheers

Dave Moore

 

Try these people for your magneto repair:-

 

Robert H Crawford & Son

 

A long established, old school family firm. As well as being excellent engineers, they have their own large collection of vintage machinery, so are sympathetic to old bits.

[Hairy-Neil]

I've also had experience of modern petrol going off after a short period of say, winter storage. I work with classic vehicles all the time and have done so for 30+ years. Recent times have brought new problems that can only be down to modern fuels. The most annoying of these is the gumming up of the fuel tank level sensor.

 

Leaded petrol is available, see:- Bayford Thrust for a supplier near you.

 

A premium product, it also carries a premium price, aproaching £2.00 per litre....

Edited March 15, 2008 by Hairy-Neil

[dave moore]

Hi Neil

Thanks for the Crawford contact. Is there an address or phone number? I tried various specialists with help from Dick Goble(Kelvin expert) to no avail.The magneto is a 6 lead model taking off alternate feeds for the 3 cylinders. Problem is the combined rotor arm/cogwheel in bakerlite. The arm is cracked and the cog has missing teeth.

Thanks for the interest

Dave

[Hairy-Neil]

Hi Neil

Thanks for the Crawford contact. Is there an address or phone number?

Dave

 

 

Frithville Boston Lincolnshire England PE22 7DU

Telephone +44 (0)1205 750367 Fax +44 (0)1205 750369

 

Is all on the website Clicky

[blackrose]

I've also had experience of modern petrol going off after a short period of say, winter storage. I work with classic vehicles all the time and have done so for 30+ years. Recent times have brought new problems that can only be down to modern fuels. The most annoying of these is the gumming up of the fuel tank level sensor.

 

Judging from the accounts above, the problem of old unleaded petrol seems to affect older engines more than newer ones.

 

Does anyone know if there is any additive one can add to unleaded to give it a longer tank life? I'm just thinking of my Honda generator. Although I run it regularly the petrol in the tank can sometimes be in there for the best part of a year without getting used up.

[Timleech]

Judging from the accounts above, the problem of old unleaded petrol seems to affect older engines more than newer ones.

 

Does anyone know if there is any additive one can add to unleaded to give it a longer tank life? I'm just thinking of my Honda generator. Although I run it regularly the petrol in the tank can sometimes be in there for the best part of a year without getting used up.

 

Short petrol life can be a real pain in little engines, such as strimmers and chainsaws, the carburettor seems to get gummed up and may need to be stripped down. Not just 2-strokes, I have a Briggs & Stratton portable genny (quite new) which suffers this way.

 

I'm don't know how much it has to do with the petrol being 'unleaded', as much as the way the fractions of oil which are used have changed as the refiners try to adjust supply to meet demand. Maybe there's someone here who understands these things, who can comment?

 

Tim

Edited March 15, 2008 by Timleech

[wotnot]

Short petrol life can be a real pain in little engines, such as strimmers and chainsaws, the carburettor seems to get gummed up and may need to be stripped down. Not just 2-strokes, I have a Briggs & Stratton portable genny (quite new) which suffers this way.

 

I'm don't know how much it has to do with the petrol being 'unleaded', as much as the way the fractions of oil which are used have changed as the refiners try to adjust supply to meet demand. Maybe there's someone here who understands these things, who can comment?

 

Tim

 

I had experience of caburettor gumming on a old Japanese 4 cylinder (therefore 4 carbs) motorcycle imported from the states. It seems that when unleaded petrol evaporates, a laquer forms that is very difficult to remove from the miniscule jets and air passages without resorting to ultrasonic cleaning. I never had this problem with leaded petrol.

 

Back to original post I would think that the biggest threat to diesel would be the 'diesel bug' causing problems with filters etc. with condensation being the main culprit.