Old(ish) diesel

[Refueler]

Yes farmers, but...... getting caught with it in your road going truck in the UK would normally result in a fine from HMRC and a follow up from the Traffic Commissioner which spelt big trouble. There was one particularly severe winter around 1980 when it was unofficially encouraged though, the foamy "winter derv" just couldn't cope leaving trucks stranded everywhere with little bonfires under the fuel tanks to try and get them going again. I remember fitting very expensive heated fuel lies to avoid this.
Anyway getting a bit OT here, I'm more concerned with the alleged 6 month shelf life of present day bio diesel, additives seem to deal with the bug issue ok. What actually happens to modern diesel as it ages? Is it just that the cetane level gets lower and the stuff won't burn?

You worry too much ....

My boats have diesel / gasoline in the tanks all through winter and I never have trouble in spring. I have 5 boats and can you imagine the hassle if that wasn't true ? That includes portable outboard tanks.

I just close the filler caps ... turn off the fuel cocks to engine after Antifreeze has been run through etc. And that's it.

Maybe I remember to throw a cupful of Bio in before winter .. if not - then it gets a cupful in spring. I will usually add fresh fuel to the tank just to compensate for any light ends lost ... but if tank has reasonable volume already in - I go with that.

 

[chriscallender]

I remember that central heating boliers can be fitted with different burner jets depending on whether you want to burn kerosene or diesel, and the pump pressure is adjusted differently. Our heating tank has a sticker on it saying 28 sec (=kerosene) on it, and I'm pretty sure there is something in the bolier installation manual for the plumber on how to modify it depending on what fuel it is using. If you try to mix diesel with kerosene the diesel is slightly heavier, so the boiler might at first be running on pretty much diesel when that finds it way to the bottom of the tank, so I'm not sure how well that would work.

Personally I wouldn't anyway, mostly because I value my heating boiler at least as much (actually - more than) a boat engine, even if it is pretty low tech. In the worst case I can replace fuel filters and get recalcitrant donkeys going again by myself but calling oil heating engineers (and getting 1000l tanks drained/disposed of) is an expensive business. If you are able to sample from the bottom of the boat's tank and it is free of any water/crud there really isn't much to worry about. If it did happen to be contaminated, it would be really easy to just transfer that problem to the new diesel anyway, unless you are very careful about getting the tank completely clean and dry before filling it again.

 

[KevinV]

I don't understand the OP - why put perfectly good, expensive, boat fuel into a tank of cheap heating oil, a use it isn't suitable for? Two years old is nothing.

 

[vyv_cox]

There are most definitely two sides to this argument. My own experience is that untreated diesel fuel in a tank that does not allow ingress of water will function perfectly well after a three-year layup due to covid and an almost two year layup for health reasons.
However, I know of several cases in which long-term stored diesel would not burn in boat heaters. The fuel sampled neither looked or smelt anything like diesel and would not run in the engine. What had happened to it is anyone's guess but I suggest that a thorough inspection is needed before trying to burn it anywhere.

 

[penberth3]

There are most definitely two sides to this argument. My own experience is that untreated diesel fuel in a tank that does not allow I guess of water will function perfectly well after a three-year layup due to covid and an almost two year layup for health reasons.
However, I know of several cases in which long-term stored diesel would not burn in boat heaters. The fuel sampled neither looked or smelt anything like diesel and would not run in the engine. What had happened to it is anyone's guess but I suggest that a thorough inspection is needed before trying to burn it anywhere.

Interesting. The more adventurous could soak a bit of rag with the diesel and light it, in a safe place. Observing the flame and smoke might give a clue.

 

[penberth3]

Yes farmers, but...... getting caught with it in your road going truck in the UK would normally result in a fine from HMRC and a follow up from the Traffic Commissioner which spelt big trouble.....

HMRC still have the mobile testing vans. They can and do confiscate offending vehicles.

 

[B27]

While the likelihood of diesel 'going off' badly enough to upset your engine may not be high, the consequences could be expensive.
Best to use your own judgement and not be blaming anyone else if it goes wrong.
In the old days, we would just put a bit in the car every week, but cars today are picky things with DPFs and cats and all that.

 

[Refueler]

While the likelihood of diesel 'going off' badly enough to upset your engine may not be high, the consequences could be expensive.
Best to use your own judgement and not be blaming anyone else if it goes wrong.
In the old days, we would just put a bit in the car every week, but cars today are picky things with DPFs and cats and all that.

The easiest way to sort is to 'blend' it off .... just add a bit to each fill up till its gone ...

 

[Ed Weiss]

Cheap Chinese diesel heater for either the boat, the workshop at home, greenhouse....