Adding oil to diesel fuel?

[Marc1]

Adding 2 stroke low ash mineral oil to diesel to prolong the life of pump and injectors is recommended for Denso common rail and older equipment. The proportion of 2 stroke oil in diesel is 3 CC or 3 millilitres per litre of fuel that converts to 0.128 fluid ounce per gallon if google is correct.
The proportion is 0.3% in fuel and the potential harm alleged by some websites of soot in the engine is nonsense due to the minuscule amount of oil and it's low ash formulation that makes it burn cleaner. Adding pure mineral oil with no additives would achieve the same result.
As far as the comments of adding sump oil to fuel, that is perfectly feasible with larger engines capable of burning heavier fuel. I have seen a fleet of passenger boats powered by detroit diesel 671 and 692 burn their sump oil by adding it to fuel in a low percentage. The trick was to polish the oil with a centrifuge that produces clean almost pristine oil. I believe that some larger ship have on board centrifuge to clean their fuel and could potentially use it for their oil. Centrifuged bunker fuel would be in the same category.
The issue of emissions with oil in the fuel, be it 2 stroke or straight mineral oil is a matter of proportions. Adding 0.3% of clean new oil to fuel would be undetectable in the exhaust even with a spectrometer. The addition of sump oil even after centrifuge is most likely a different matter due to contaminant that are much harder to eliminate, and I am sure you don't have a centrifuge anyway ... even when they are rather easy to build. the Simple Centrifuge website is a good source if you want to build one.
As for Biodiesel, the erratic nature of sources of cheap oil or fat, the political, almost religious nature of their highly motivated supporters, that tend to obscure the many disadvantages and dangers and toot their small advantages makes it an unlikely if not dangerous fuel for your boat.
That is not to say that you couldn't use it for an older stationary pump like an old Lister chuffing along to pump water or turn a generator. A bit like using kero to fuel an older hit and miss petrol motor. Each to his own I suppose. I remember as a student adding 30% kero to the fuel tank of my 1928 Buick to save a few bobs

[ejjawhite]

Originally Posted by O_salt

A friend of mine has bought a new Volvo diesel engine and the salesman / Installer is telling him to add 1% 2-stroke motor oil to his diesel fuel to help lubricate the engine.

Has anybody else ever heard of this?

A friend of mine ads about 1/2 quart of transmission fluid every time he fills his diesel tank (40 gal).. he said a diesel mechanic told him to do that.
I started doing it intermittently last year operating my Yanmar 3HM35F, with no ill effects.

[Diesel Bill]

I run my 96 Dodge diesel with old school mechanical P-7100 million mile mechanical pump, and my 96 Benz e-300 diesel with mechanical inline jerk pump on ulsd fuel. I treat them on occasion with a slug of 2 stroke oil. Modern common rail HP pumps shouldn't need any
added lubricants as the pumps were designed for modern low sulfur fuels. Old style mechanical pumps with plungers and barrels rely on the lubricity of the fuel to keep wear at bay. Any one remember back in the 60's and 70's seeing cars on the road with great clouds of white smoke billowing out of the exhaust? This was transmission oil being pulled up from the transmission through the perforated modulator valve diaphragm, up the vacuum line to the intake manifold and being burned in the engine. ATF is not designed to be burned. Neither is 4 stroke engine oil, as it has a anti wear additive package which when burned leave a coating on piston crown, valve heads and combustion chamber. Modern 2 stroke oils burn clean without forming ash and deposits.
When I attended Caterpillar school we had to set up an injector pump for a 3208 series engine and I remember the clearances were measured in the millionths of an inch. I'm sure there's better things than 2 stroke oil to add, but I still have some in the garage so I'll still use it till it's gone. Just don't get suckered by the snake oil salesman.

[geoleo]

Originally Posted by MartinR

The Devil himself heard of it.

[a64pilot]

Originally Posted by TideTime

Several years ago, I had an certified Yanmar diesel mechanic recommend the addition of a small amount of Mystery Oil to my thirty year old Yanmar 1GM10. However, I doubt if that would be recommended for a new diesel and certainly not if owner's manual advised against it!

MMO has been added to aircraft fuel forever, it was what it was made for.
I always though it pure snake oil, but have seen at least one R-1340 engine that if it doesn’t get MMO in its fuel it will stick valves.

It is NOT FAA approved even though it’s been widely used since I believe before WWII.

[a64pilot]

Originally Posted by MarkSF

When VW's high pressure pumps were failing all over the place, it turned out that a surprisingly small amount of gasoline in diesel will reduce the lubricity below the acceptable level, like 1-2%.



Be careful where you buy your diesel. I've bought diesel that actually smelled like gasoline, there was that much gas in it. Didn't go back to that station again.

In the manual for my Golf Diesel it stated the amount of gasoline to add to fuel if winter fuel could not be purchased.

[a64pilot]

Originally Posted by newhaul

the Mercon dextron series of transmission fluid is a great injector cleaner for those of us that still have the good old mechanical systems( don't know about electronic injectors )
it will also clean out all of the soft carbon deposits in the engine . It is after all a petroleum based soap. Keeps my old md2 singing like a sewing machine.

Way back with old Mercedes Diesels, when they started knocking at idle like they did when cold, it meant that the injectors were dirty, a quart or two of transmission fluid in the tank would clear it up.
Transmission fluid is very high detergent oil.

[Bentwings]

Modern trans oil is not the same as old school trans oil. It’s hard to even get type F now.

Also I agree on additives to the diesel. The old Cummins 12 valve worked fine on about anything that would burn. As the ultra low came into being the two stroke oils were added as they were pretty clean burning. As noted the electronic fuel injectors and pumps are designed to run on modern diesel fuel. I you have good 2% or 5% bio diesel it’s about as good as it gets. You just have to keep after the fuel filters. My son drives over the road in brand new trucks and they don’t add anything but DEF in the DEF tank. Some stations don’t take good care of their tanks but if problems surface everyone in the country will soon know about it and they won’t be able to give the remaining diesel away.

If you get your diesel from the stations that cater to the big trucks you can be pretty sure it’s good. Those of us up here where it gets really cold do the same as the truck stations get winterized fuel daily. My old 24 valve Cummins will start start at -25 F every time.

[Lippe]

Originally Posted by Diesel Bill

I run my 96 Dodge diesel with old school mechanical P-7100 million mile mechanical pump, and my 96 Benz e-300 diesel with mechanical inline jerk pump on ulsd fuel. I treat them on occasion with a slug of 2 stroke oil. Modern common rail HP pumps shouldn't need any
added lubricants as the pumps were designed for modern low sulfur fuels. Old style mechanical pumps with plungers and barrels rely on the lubricity of the fuel to keep wear at bay. Any one remember back in the 60's and 70's seeing cars on the road with great clouds of white smoke billowing out of the exhaust? This was transmission oil being pulled up from the transmission through the perforated modulator valve diaphragm, up the vacuum line to the intake manifold and being burned in the engine. ATF is not designed to be burned. Neither is 4 stroke engine oil, as it has a anti wear additive package which when burned leave a coating on piston crown, valve heads and combustion chamber. Modern 2 stroke oils burn clean without forming ash and deposits.
When I attended Caterpillar school we had to set up an injector pump for a 3208 series engine and I remember the clearances were measured in the millionths of an inch. I'm sure there's better things than 2 stroke oil to add, but I still have some in the garage so I'll still use it till it's gone. Just don't get suckered by the snake oil salesman.

Thank you Diesel Bill for balanced and sensible comment made by a man who knows what he is talking about. It is horrible to see people writing about diesel engines as if they were all the same animal. Someone is even comparing to jet engines. Modern engines do not accept additives even if old engines did. I recall my teacher telling that in a very old diesel engines onboard a small ship he was serving the engine had a cup on cylinder head for (i am not sure about correct english word) glow plug? He put a cigarette stub to the cup when starting. That is another thing not to be done on modern diesel engines.

[mako]

I wonder if this idea is related to the practice of feeding used motor oil back into the diesel fuel tanks?

[MartinR]

After refining, the ULSD is analysed at the refinery and lubricants are added to specification. This specification is actually different for different countries. So, there is no need to add oil for lubricity.

The other issue is viscosity. ULSD has a lower viscosity than traditional diesel fuels. This means that it works very well in modern injection pumps, where tolerances are extremely small. With older type pumps you will loose some power, due to leakage of fuel around the piston. For this, addition of bio diesel, as low as 2% will help, maybe even two stroke oil, I have no data on this. Bio diesel we definitely do not want in our fuels.

[newhaul]

Originally Posted by Lippe

Thank you Diesel Bill for balanced and sensible comment made by a man who knows what he is talking about. It is horrible to see people writing about diesel engines as if they were all the same animal. Someone is even comparing to jet engines. Modern engines do not accept additives even if old engines did. I recall my teacher telling that in a very old diesel engines onboard a small ship he was serving the engine had a cup on cylinder head for (i am not sure about correct english word) glow plug? He put a cigarette stub to the cup when starting. That is another thing not to be done on modern diesel engines.

i had a bmw d12 and it had a cigarette cup on it and no it wasn't for a cigarette it just was shaped like one . It was for extra fuel for cold starting to seal possible leaking rings . Till the engine was warmed up.