Diesel - does it go off?

Submitted: Wednesday, Jun 24, 2009 at 14:44
ThreadID: 70115 Views:9578 Replies:6 FollowUps:10
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Hello there,

I've had some diesel in a container for about 18 months - is it ok to use?

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Reply By: Nargun51 - Wednesday, Jun 24, 2009 at 15:12

Wednesday, Jun 24, 2009 at 15:12
Petrol only lasts about 6 months until the more volatile components have evaporated out to the point where it raise the ignition temperature, (the fffshhh when you open the can), with a resulting loss in power (in January my daughter brought home a can of 2 stroke fuel as requested. Could NOT get the brush cutter started until I asked whether she had bought it from the drum of premixed fuel…went down and bought some oil and petrol and it started first pull)

As diesel is a “heavier” fuel the evaporation of the more volatile components would be less of a consequence and the ignition is based on compression rather than introducing a spark to a gas/air mixture. However; if the volatile components in the diesel have evaporated below the level to allow for ignition, the engine will just be compressing oil with the possibility of damage to the motor through hydrolicking (sp?)

Depends on how much you have and how it has been stored? 5 litres into a 90 litre tank would probably have no consequences… but there could be a lack of power.

Wouldn’t fill the tank with it though. And there is always the risk of moist air having got into the drum which has condensed out during colder weather…

AnswerID: 371654

Follow Up By: BuggerBoggedAgain - Wednesday, Jun 24, 2009 at 16:36

Wednesday, Jun 24, 2009 at 16:36
Follow on about the petrol, have you notice in films about finding a deserted airplane or vehicle with fuel still in it and it fires up, talk about a load of cattle dung, as if petrol lasts 30 yrs, producers must think we're all dimwits
FollowupID: 638925

Follow Up By: Mal58 - Wednesday, Jun 24, 2009 at 17:04

Wednesday, Jun 24, 2009 at 17:04
A bit off topic.

I have a jerry can of petrol that is about 7 years old.

I use it occasionally in the lawn mower. (don't mow the lawns much)

Seems to work OK, so I guess it depends on storage conditions.
FollowupID: 638929

Follow Up By: Robin Miller - Wednesday, Jun 24, 2009 at 18:47

Wednesday, Jun 24, 2009 at 18:47
Hi Mal

I reckon one of my best investments ever was buying a 44 of petrol and keeping it for around 10 years before use (actually the container base rusted).

I agree that some of the volatile components are lost over time and this relates to how good the container is as you say , but over the ten years the cost of the fuel rose enormously and seriously out performed some super funds I had.
Robin Miller

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FollowupID: 638954

Reply By: tim_c - Wednesday, Jun 24, 2009 at 15:37

Wednesday, Jun 24, 2009 at 15:37
If in doubt, just tip a small amount in each time you fill the tank - any problems (unless it's got bits in it) should be dilute enough not to cause any problems.

You won't hydraulic your engine by using bad fuel (unless you pour it into the air cleaner while the engine is running!). Hydraulicking only happens when the engine sucks in a whole lot of non-compressible fluid/liquid through the air intake - air is compressible but water etc. is not! The fuel system doesn't deliver enough liquid to cause this problem, regardless of what fluid it is (diesel is no more compressible than oil).
AnswerID: 371656

Follow Up By: Nargun51 - Wednesday, Jun 24, 2009 at 16:54

Wednesday, Jun 24, 2009 at 16:54

I have no experience with diesels from a mechanical standpoint; only filling them up. I have always read, and been told, that water in the fuel is a strict no/no for them and even small amounts can cause issues, and is the reason for the water sensor on the fuel filter.

It’s been 35 years since I have done any physics, and my memory is a bit sketchy, but I was taught that compression of a gas or fluid raises its temperature (the old bike pump experiment). In a diesel, the stronger compression of the diesel raises the temperature of the fuel so that the volatile fractions within the fuel reach the ignition point and “spontaneously” ignite. Therefore, an ignition source is not needed (apart from the glow plug until such time as engine block heats up)

The logic in my answer, (and please tell me where I’m wrong in either practice or theory) is that if enough “light” or volatile fractions of the diesel have evaporated, the compression of the motor will not ignite the fuel and the motor will be compressing oil which is not being burnt and added to on each pulse of the injectors. As the fuel is not igniting and expanding, this is not being discharged through the exhaust either

As I said, my logic could be totally wrong and diesels may not be as susceptible to hydraulic issues as I have thought
FollowupID: 638928

Follow Up By: Member - Rodney B- Wednesday, Jun 24, 2009 at 17:56

Wednesday, Jun 24, 2009 at 17:56
It may not be ignited but it is certainly being pushed out the exhaust on every second revolution and the quantities as so small there is no chance of Hydraulicing

FollowupID: 638939

Follow Up By: Malleerv - Wednesday, Jun 24, 2009 at 18:04

Wednesday, Jun 24, 2009 at 18:04
The injectors would not deliver enough fuel to cause an engine to hydraulic. Also diesel engines can run on sump oil when warm so even if the diesel has lost its volatility it should still burn.
Any water in the system will be burnt away in combustion but may cause problems with the injectors and pump not delivering correct amounts of fuel.

Cheers Matt
FollowupID: 638941

Follow Up By: tim_c - Wednesday, Jun 24, 2009 at 18:08

Wednesday, Jun 24, 2009 at 18:08
Yes, water in the fuel is bad news but as far as I know, it's not because of the compression. The problem is more likely to do with lubrication and cooling of the high-pressure fuel pump and injectors (oily diesel is far better for this than water) and the potential for rust in these components.

The injectors only deliver a very small amount of fuel each pulse and this is dispersed so finely as a 'mist' (ideally it is virtually in vapour form) so unburnt fuel shouldn't accumulate in the combustion chamber because it will be forced out during each exhaust cycle, along with everything else. Incomplete/inefficient combustion won't cause fuel to accumulate in the combustion chamber - in fact, incomplete combustion is the reason for the black smoke from poorly maintained diesels. The only way I know to get enough liquid into the combustion chamber quickly enough to cause damage (ie. so it isn't forced out on each exhaust cycle) is in through the air intake.

As far as I understand, the problem with storing diesel for long periods of time relate mainly to the likelihood of condensation in the storage tank (therefore adding water to the fuel) and the potential for algae growth.
FollowupID: 638942

Follow Up By: Nargun51 - Thursday, Jun 25, 2009 at 11:30

Thursday, Jun 25, 2009 at 11:30
Thank you to all for the information, which clearly gave the reasons, experiences and logic to correct behind my insufficient and misguided (deluded?) response.

Another example of the positive role that EO can provide
FollowupID: 639054

Reply By: olcoolone - Wednesday, Jun 24, 2009 at 15:59

Wednesday, Jun 24, 2009 at 15:59
On older diesels it should not be a problem but as said above mix it with fresh diesel and use it over time.

If you are running the newer Common Rail Diesel I would give it a miss.
AnswerID: 371659

Reply By: Shaker - Wednesday, Jun 24, 2009 at 16:37

Wednesday, Jun 24, 2009 at 16:37
According to BP ........

BP Ultimate Diesel is a Combustible C1 product for storage and handling regulations and legislation requirements in Australia.
Storage of diesel in drums or bulk tanks needs to be properly managed to maintain product quality and storage life. The following procedures will ensure that the fuel remains fit for use.
Ensure that the grade of fuel (winter or summer) is suited to the seasonal period when it will be used.
The oldest fuel shall always be used first.
Drain water and sediment from bulk tanks at regular intervals, start with daily de-watering in the morning when the fuel is coolest, extend drain intervals if no water is detected.

Do not use copper, brass or zinc in contact with the fuel.
Ensure that horizontal tanks slope to the drain valve so that drainage is not impeded.
In dusty areas consider a 10 micron air breather filter to remove airborne dust.
Do not let filling hoses drop onto the ground or dirt.
When stored correctly BP Ultimate Diesel will normally keep for 12 months without deteriorating but should not be mixed with old fuel as this will shorten the storage life of the new fuel.

For further information, please call the
BP Lubricants and Fuels Technical Helpline
1300 139 700

AnswerID: 371665

Follow Up By: trainslux - Wednesday, Jun 24, 2009 at 17:37

Wednesday, Jun 24, 2009 at 17:37
Of interest is this.

Diesel's biggest problem is alge growth.
This happens when you have water in with the fuel.
The alge grows on the barrier between the water and the fuel.
The alge feeds on the sulphur.

Now we have low sulphur fuel compared to a few years ago, so the longevity of the fuel, if kept in an airtight, free from water environment is pretty good.

Nulon state that their diesel fuel additive has benefits for prolonged storage of fuel.

Diesel will store for well over 1 year if kept out of excessive heat, and is clean to start with.
Add a dose of nulon, or other additives that prolong storage life, and your good to go.
Petrol on the other hand does not have the same abilty to store due to its additives, and volitile nature.
So, diesel is ideal for those generators that only get used every now and then, and for waterpumps etc for the very same reason.

With our farm machinery, and bulk fuel, we had the same questions, and after some investigation, and research, have kept diesel for many years without problems.

with bulk storage, fit a moisture trap, and a basic filter on the end of that, ensure the tank is free from moisture, and contaminates to begin with, and your good to go.

Just my findings after storing fuel between times of use on the farm.

FollowupID: 638933

Reply By: RobAck - Wednesday, Jun 24, 2009 at 17:37

Wednesday, Jun 24, 2009 at 17:37
It should be OK but the condition of the internals of the JC are always of concern. So pour it into a funnel with a decent mesh filter screen to remove any bits and pieces before putting into the fuel tank itself.

As well diesel can be subject to a fungus/bacteria that actually grows on the fuel when left for long periods. It blocks fuel lines and filters and can ruin injectors.

So there really is no reason to keep fuel for long periods in JC's at all


AnswerID: 371673

Follow Up By: Member - loris G (NSW) - Wednesday, Jun 24, 2009 at 18:21

Wednesday, Jun 24, 2009 at 18:21
Wow!! Thanks for all the advice. I'll filter it in slowly. I have a 75 series troopy.
FollowupID: 638944

Reply By: get outmore - Thursday, Jun 25, 2009 at 11:02

Thursday, Jun 25, 2009 at 11:02
yes it will be fine ive done it a few times used fuel over 12 months old - last time was 2 jerries into an empty tank with no worries
AnswerID: 371770

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