Lubricity of diesel

[RalphVa]

A friend of mine stopped by the other day. He works at a place that uses Stoddard solution. He said it is apparently a cut between kerosene and diesel and was wondering about reusing it in a diesel engine. He was worried about keeping the same lubricity.

I'm wondering if anyone has a technical definition of just what lubricity is needed in diesel injection pumps? I told him to maybe get some diesel and measure the viscosity of it at a couple temperatures. Then maybe mix in some ATF (which is on the heavy end of a standard diesel cut) in to get the viscosity with the Stoddard solution.

Mercedes Benz, however, have been using what looks like almost the same mechanical injector pumps for gasoline and diesel engines since about the 1950s (for gasoline and diesel before that).

Ralph

 

[RalphVa]

Found it. It's in ASTM D975. Here's a web site that gives the specs: Link

Looked up Stoddard solution, too. It's between gasoline and kerosene somewhere in that boiling range. Pretty light stuff to be using in a diesel.

Ralph

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[Darren]

Lubricity is related to the sulfur contained in the fuel. More sulfur, more lubricity. Less sulfur, less lubricity.

 

[SkyPup]

Sulfur has nothing to do with lubricity.

 

[Soundguy]

Ok.. got a question for you.. wasn't this brought up a while back.. and while it was discussed that sulfur itself wasn't the lubricating component.. that in the process of removing the sulfur ( to meet new fuel standards ).. had the side effect of lowering the lubricity? thus low sulfer fuel was 'less' lubricating?..( even if it wasn't the sulfur that was the lubricant..)

Soundguy

 

[arthr31]

ah, i think that is correct. thereby meaning that lower sulfer = less lubricity, therefore lowering the sulfer effects lubricity.

hey guys, add some powerservice and forget about worrying about this stuff!! -Art

 

[Soundguy]

I love power service!

Soundguy

 

[cp1969]

</font><font color="blue" class="small">( ...that in the process of removing the sulfur ( to meet new fuel standards ).. had the side effect of lowering the lubricity? )</font>

Maybe the best way to answer this is: It can, and did, (very early in program to remove sulfur from diesel) but doesn't any more.

The reduction in lubricity caused by the process of removing sulfur (not the absence of sulfur itself; Skypup is right--sulfur is not a lubricant) is well understood and compensated for by refineries. The end user need not worry or take any action to supplement lubricity.

As I understand it, the lubricity problem cropped up it Norway or Sweden way back when the sulfur reduction program kicked off. It is not a problem in the US and never was. However, perpetuating the tale has sold countless cases of unnecessary lubrication-supplement additives. All it has to say is "Improves Lubricity" on the bottle and someone will infer that lubricity of retail fuel is insufficient, which it is not.

 

[HGM]

I agree that lubricity is not a big issue in quality fuel. But I dont think you can ever have too much lubricity /forums/images/graemlins/grin.gif..

The additives are alot more than just a lubricity additive though. The cetane boost and anti-gel and anti algae properties of the additives make them very well worth the cost. I am a firm believer in diesel fuel additives, mainly for cetane boost, lubricity is an added bonus. /forums/images/graemlins/grin.gif

 

[pruntyc]

I just read a report that the Mississippi State University agricultural engineer, Herb Wilcutt made. It says, "The removal of sulfur is going to be great for the environment in terms of eliminating pollutants, but it will cause problems for diesel engines because sulfur helps lubricate the fuel pumps and the engine itself. Something will have to be added to diesel to restore the lubrication lost by removing the sulfur." And goes on to say that the use of biodiesel will do that, if used. Not wanting to start something, but I'm afraid I have to believe an engineer, that works for the State University, in the Agricultural department, above you guys. And he is says sulfur helps lubricate, then I have to believe it does.