Is a small amount of lube oil in diesel tank a problem?

[LittleSister]

Is 'contamination' of diesel fuel with a small amount - say maximum 5% - of standard mineral engine lube oil likely to be problematic? Does it have the potential to either harm e.g. injectors, or badly affecting engine running?

The background is that I'm contemplating draining my boat's diesel tank in order to clean it out as best as possible. There's maybe 20 to 30 litres of diesel in there. I was wondering what to decant the fuel into, and was given a large almost empty lubricating oil drum that could be just the ticket.

There's a smallish amount of clean new lube oil remaining in the drum - a cup or two in the bottom (I may be able to get half of which out by suction tube), plus whatever clings to the walls. The shape of the top of the container and its cap means that it would not be possible to drain it all out, therefore there will be an amount of this in the diesel when I replace it in the tank (hopefully via some sort of filter/polishing arrangement yet to be decided/organised).

(And no, washing the drum out with petrol or whatever would not be practicable!)

 

[Alex_Blackwood]

Is 'contamination' of diesel fuel with a small amount - say maximum 5% - of standard mineral engine lube oil likely to be problematic? Does it have the potential to either harm e.g. injectors, or badly affecting engine running?

The background is that I'm contemplating draining my boat's diesel tank in order to clean it out as best as possible. There's maybe 20 to 30 litres of diesel in there. I was wondering what to decant the fuel into, and was given a large almost empty lubricating oil drum that could be just the ticket.

There's a smallish amount of clean new lube oil remaining in the drum - a cup or two in the bottom (I may be able to get half of which out by suction tube), plus whatever clings to the walls. The shape of the top of the container and its cap means that it would not be possible to drain it all out, therefore there will be an amount of this in the diesel when I replace it in the tank (hopefully via some sort of filter/polishing arrangement yet to be decided/organised).

(And no, washing the drum out with petrol or whatever would not be practicable!)

Shouldn't be a problem. Might smoke a bit !

 

[rightstuff]

Won't be a problem

 

[Refueler]

Not a problem at all .......

 

[Neil]

Wasn't the original engine design by diesel supposed to be fuelled by oil anyway?

 

[Beneteau381]

Is 'contamination' of diesel fuel with a small amount - say maximum 5% - of standard mineral engine lube oil likely to be problematic? Does it have the potential to either harm e.g. injectors, or badly affecting engine running?

The background is that I'm contemplating draining my boat's diesel tank in order to clean it out as best as possible. There's maybe 20 to 30 litres of diesel in there. I was wondering what to decant the fuel into, and was given a large almost empty lubricating oil drum that could be just the ticket.

There's a smallish amount of clean new lube oil remaining in the drum - a cup or two in the bottom (I may be able to get half of which out by suction tube), plus whatever clings to the walls. The shape of the top of the container and its cap means that it would not be possible to drain it all out, therefore there will be an amount of this in the diesel when I replace it in the tank (hopefully via some sort of filter/polishing arrangement yet to be decided/organised).

(And no, washing the drum out with petrol or whatever would not be practicable!)

See here for the Gardner handbook pic on how to use old lube oil
Oil filters

 

[DownWest]

Wasn't the original engine design by diesel supposed to be fuelled by oil anyway?

Think Otto Diesel used coal dust..

Since diesels with loose clearances or overfilled sumps tend to run away from lub leakage up into the cylinder, I can't see a problem with 5% in the fuel.

 

[Refueler]

At various times even ships engines have been tested with Coal Slurry as a fuel.

Given the emissions tests now conducted on cars - oil burnt in engines is a factor being reduced ..... not a problem on a boat of course.

 

[fisherman]

My Lister had oil injector plugs on the air inlet to prime it with lube oil.

 

[LittleSister]

Thank you all.

 

[DownWest]

My Lister had oil injector plugs on the air inlet to prime it with lube oil.

I sorted quite a few Lister gensets. None had an oil injector, but the crappy 3kva Petters did have a place to put in a bit of lub oil to help things along..

Little story:
Arquitect friend bought an old fishing boat in the Algarve. Called Kingfisher.. It had a two pot Lister. He had no end of trouble getting it to run. Heads off, injection tested, no result. Ran, but smokey and no power.
Old fisher guy was passing, knew the boat.. listened to the ills. Pull a bit of fuel. So friend did, fisher guy sniffed it and pronounced it 'dead'. Seems that it had been sitting a long time in the heat and the volatiles had gone? Fresh fuel cured it.
Roll on several years.. Same friend an I are getting ready to leave Vilamoura for Gib, in his 36ft classic cold moulded sloop. We notice a boat puttering by... Yes, it was Kingfisher, with a very tanned owner lounging by the tiller. Hi! where have you come from? Greece...

 

[rotrax]

Wasn't the original engine design by diesel supposed to be fuelled by oil anyway?

I thought it was finely powdered coal dust. They certainly had one running on that fuel.

 

[ChromeDome]

Many owners pre commonrail et al added two stroke oil to the diesel car tank on a regular basis.
Made them run smoother, allegedly

 

[QBhoy]

More likely it will be good for it ! Give the fuel pump some lubrication, that it’s been starved of, with the fuel we get these days. Not unknown for guys to run some 2 stroke in their fuel for this reason. Good for old school engines that aren’t of the common rail modern type. Can even restore some compression too !

 

[Boater Sam]

I used to dump the sump and gearbox oil into the diesel, never did any harm.

 

[Refueler]

More likely it will be good for it ! Give the fuel pump some lubrication, that it’s been starved of, with the fuel we get these days. Not unknown for guys to run some 2 stroke in their fuel for this reason. Good for old school engines that aren’t of the common rail modern type. Can even restore some compression too !

Todays Diesel is tested specifically for Lubricity and additives put when needed. The other factor is that a common addition to Gas Oil (Diesel) is LCO .... Light Cycle Oil ..... nearest equivalent you could find is Sewing Machine Oil ....

I do not advise adding further Lub oil to diesel in your car ..... especially if you are soon to have emissions test.

 

[Tamar]

It will be absolutely fine. Any old oil I have left after a service on my boat that I can't fit into the container I dump in the fuel tank, no problems, not even smoke.

 

[The Q]

When the first Sulphur free diesel fuel came out ( in California I believe) they cocked up , as sulphur provided some of the lubrication. So it for a while became common to add oil in small quantities.
In an OLD diesel adding Two stroke oil, can actually reduce smoke, and it's common on old Landrovers ( 200ml per 45ltr)

 

[Adios]

Bung some paraffin in if you're doing a cocktail. Great for the injectors

 

[Refueler]

Bung some paraffin in if you're doing a cocktail. Great for the injectors

Parafin or Kerosine - is good for winterising summer grade and that is its only benefit. It has no benefit whatsoever as a lubricant in diesel.