Bacterial Decay in Old Diesel

[Stephen Mawson]

A few days ago I got out from the back of my garage an old 1960s genuine 20 litre military jerry-can -- no need to ask why -- only to find that it was already nearly full of diesel. It must have been there for at least eight years, possibly ten or twelve, and I had completely forgotten about it.

After the earlier thread on this subject I was expecting there to be bacterial sludge at the bottom so I decanted it carefully into another container intending to stop at the first sign of sludge. No sludge at all, apparently clean diesel right to the bottom except for a few flecks of red lead paint from the inside of the can.

Question: is it likely to be OK to use? Should I use it only mixed with x% of new diesel?

Many thanks for any thoughts,

Stephen

[The Natural Philosopher]

Id say the latter for the following reasons, which may or may not be valid.

All commercial petroleum fuel distillates area mixture of things. These are adjusted with more expensive additives to control to within reasonable limits such things as sulphur levels, gummy residue potential and water absorption as well as viscosity and something akin to octane number.

If the can is not 100% gas tight over time these will evaporate differentially leading to a preponderance of the thicker gummier stuff and a loss of the lighter and possibly better igniting fractions.

so you need to dilute it with good fuel to restore the balance somewhat. It will probably work, and if its some old tractor, work undiluted as well, but for a modern car it might end up smokey or bunging up a filter. Or being difficult to start.

I'd be tempted to fill the tank 3/4 and top up with the can, and repeat till can empty or, it there's not much in the can top that up with fresh.

In short it probably will work undiluted, possbly rather poorly or possibly just fine,. But why risk it? mix with new and reduce the risk to almost zero.

What was IN fuel 20 years ago anyway?

[Fredxx]

If petrol I would totally agree, but diesel doesn't generally have any light components which would evaporate.

[newshound]

Since it has come out "clean", there was probably no free water in there: this is what "bugs" need to grow. Modern "biodiesel" would be unlikely to have survived so well.

I think "evaporating fractions" is more of an issue with petrol than diesel. Diesel is of course less volatile anyway than petrol.

One of the big differences is that your old diesel will have significantly higher sulphur levels, maybe 1000 ppm compared to the current 20 ppm for road vehicles.

As TMP says, it depends a bit on what you want to put it in. I think I would use it "neat" in a tractor or (say) a Series 3 Landy or similar vehicle.

Is there anything in expensive German diesels which wouldn't like the sulphur? It wouldn't do catalysts a lot of good, for example.

Diluted 10:1 each time I can't see there being very much risk. Cross posted to uk.rec.car.maintenance because there are some very knowledgable guys there.

[The Natural Philosopher]

diesel itself is a light fraction that will in time evaporate.

spill some. It takes about 2 years before the smell has completely gone

And if it don't have any light fractions it wouldn't smell would it.

[NT]

So in a closed metal container, not a significant issue at all.

[The Natural Philosopher]

this is 10 years mate.

Not 2.

[Paul - xxx]

If you're worried about it, I'll 'ave it .. pour it straight into the Landrover.

You anywhere near Doncaster? ;)

[Stephen Mawson]

Sorry Paul, I'm in South London and I too have a Land Rover -- I wouldn't hesitate much putting it into my old Series I but a Discovery is a bit fussier.

Thanks to all for the advice -- I think I'll use it, but diluted with new diesel.

Stephen

[Paul - xxx]

Mine's a Disco 300 Tdi, been running it on s**te for years, it has better emissions than when it was new .. ;)