ACTUALLY don't get all smug just yet. None of those links is to an actual MB document, only threads discussing it and third party products. Mercedes only approves it for temporary use, not every fill up.

Clean, fresh Diesel is all that should be used. Additives are a waste of money except where gelling is a concern.

Notice the key highlighted in that sentence. I too got a similar large jump in economy on a long highway trip (26.6 to 29.6mpg). The jump in economy is not the result of the 2-stroke oil but of the highway trip.

A small amount of 2-stroke oil alone cannot miraculously produce a 10% jump in fuel efficiency.

Forced, you realize I mean nothing personal by the reply, just intending to indicate that Mercedes does in fact state it is okay to add this to a diesel engine, that is what we're debating here, not whether or not it should be used each fill up, thats just what I do.....

As to the 70 miles, I do the same 140 mile trip 5 days a week in the SD, and calculate my fuel economy on each fill up....I always averaged in the 26 MPG range....then I used 2 cycle, 29.6 MPG, then I ran straight diesel, 25.8, then last two tanks have been 2 cycle, 29.67 and 29.74....same trips, same driving style (with the exception of about 57 miles of city driving on the last tank, which I never do in that car).....I'm just simply reporting my results......

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2015 E250 Bluetec Black/designo Sand
2014 GLK250 Bluetec Iridium Silver/Almond
1999 E320 Sedan Bordeaux Red/ Parchment
1999 E270CDI Estate Black Opal/Black
1983 300SD Champagne/Palomino Leather
1982 300SD Silver Blue/ Pacific Blue Leather

LOL, so did the 2 stroke oil magically increase the density of the diesel fuel by 10%, or did it magically increase it's heating value by 10%? Either way, my old thermodynamics professor would be very impressed that you've disproved some very basic physics and chemistry.

How about changing some lead into gold when you get a chance?

LOL, you know, sometimes, its just not worth it....

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2015 E250 Bluetec Black/designo Sand
2014 GLK250 Bluetec Iridium Silver/Almond
1999 E320 Sedan Bordeaux Red/ Parchment
1999 E270CDI Estate Black Opal/Black
1983 300SD Champagne/Palomino Leather
1982 300SD Silver Blue/ Pacific Blue Leather

You know guys, this stuff is probably harmless and it might even have some favorable lubrication effects on ULSD. I'm pretty confident that you are not doing any damage, but an additive simply will not increase your fuel mileage by 10%. Assuming this is not a placebo effect, it is more likely that you are seeing better mileage because you filled up with ULSD from a different batch.

I don't think the source of ignition is an issue at all.

Haven't tried it on the Benz yet-but both the GM 6.2 and Cummins both get 'round 2 MPG better with it, the Cummins seems half as loud with it as without it-some people have advanced the theory that 2-stroke makes the fuel burn as it did in the old high-sulfur days. I'm using Citgo Outboard TCW-3 conventional, the Meijer stores around here were GIVING it away at under $3/gallon! Whole lot cheaper than Power Service or Stanadyne!

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1982 300DT 190K (Diesel Purge + synthetic oil=smoothness at last!!!)
2004 Ford E-350 6.0 L PSD 227K
2006 Dodge Ram 3500 SRW HO Cummins 4X4 48RE 42K (brute force tow vehicle)
2005 Scion xB wife's rolling pop can
1993 GMC Sierra C3500 6.2 142K

I am fairly new here but there really is no call to go out of your way to be rude, it looks bad on you.
Anyway to the point:

Much of the power generated by an engine is used in driving the engine. If (just saying 'IF") an additive does reduce friction it WILL deliver more power and burn less fuel. No Magic, it is obvious.

I am not quoting any old thermodynamics profs, (I don't have any). I never studied Physics or chem either. But in Kindergarten I learned to share, and a nice lady taught me to not be rude.

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Thanx,
Alberta Luthier
1983 300CD ('Stinky')155k miles, 2.47 diff, EGR removed, AAZ injectors with 265 nozzles from Sean,and vogtland lowering springs.
1984 300SD ('Old Blue')150k Klicks from Japan originally, came with rear head rests, no sunroof and never had an EGR

Sorry if I was rude, I'm just trying to deal with misinformation on the forum.

Regarding the use of fuel additives, we are talking about the lubricity of the fuel, not the engine oil. The contribution of the friction in the injection pump is a tiny contribution to the overall engine friction. I would agree that improving the lubricity of the engine oil can have a measurable effect on the fuel consumption (which is part of the reason new cars specify very low viscosity oils). The only possible advantage of this additive is reduced wear in the fuel system, which has nothing to do with fuel mileage.

hmmmmmm. You got a point, maybe I ought to use some 2 stroke in the crankcase??? Or maybe I better leave that to the folks who do understand the oil chemistry...
But I think we all sort of tip our heads a bit sideways when you add something and the whole engine gets quieter and smoother.( oil, trany fluid, DP, or snake oil). That aways gets my attention, but maybe a quieter engine just seems better because of my limited diesel experience.

__________________
Thanx,
Alberta Luthier
1983 300CD ('Stinky')155k miles, 2.47 diff, EGR removed, AAZ injectors with 265 nozzles from Sean,and vogtland lowering springs.
1984 300SD ('Old Blue')150k Klicks from Japan originally, came with rear head rests, no sunroof and never had an EGR

I believe the quieter engine at idle has more to do with changing the combustion characteristics of the fuel. It is quite possible that a slower burning fuel will result in a quieter engine, a bit like retarding the timing on a gasoline engine.

It would be very cool to do a series of Dyno runs with some different fuel/additive combos. But with maybe tweeking timing to fine tune optimum performance from each it would take some serious $.
Hell we ought to get a government grant for the research (god knows they piss it away on the stupidest things, well they do up here anyway).... But that would take friends in high places... and I'd rather stick needles in my eyes than cozy up to a politician

__________________
Thanx,
Alberta Luthier
1983 300CD ('Stinky')155k miles, 2.47 diff, EGR removed, AAZ injectors with 265 nozzles from Sean,and vogtland lowering springs.
1984 300SD ('Old Blue')150k Klicks from Japan originally, came with rear head rests, no sunroof and never had an EGR

People arguing against the mileage increase, take note.

There is a scientifically conducted study cited below and now data from Mercedes Benz diesel owners (and two other different diesel engines) using different additives that concur with its results.

The onus is now on you (all) to present empirical data to counter this.
I thought this group was fairly scientifically oriented.

In case people sometimes do not bother to read links -- a mileage increase resulted from engine oil improvements and -- independently -- mileage increases (specific fuel consumption) resulted from diesel fuel additives that improved the lubricity of the fuel.

That testing was done in a sophisticated university engine lab with a high degree of rigor.

Tsk, tsk, tsk.

When I walked up to the checkout with six bottles the clerk said that she knew what I was up to. Oh?

A big fishing trip.

Something like that.


Edit: I went through a bit of some Mercedes owners calling the products that I make "snake oil". [crank scrapers] Particularly with respect to diesels. When I finally got a loose 603 pan it had five of them in there.

Five.

Nothing of the sort. The thermodynamic equilibrium has simply been shifted. Some of the energy that was being lost to friction is now available as increased mechanical motion.

Same thing happens with reduced friction motor oils. Or light tension piston rings. And so on.

No need to appeal to transmutation and philosopher stones.