19 mpg

[Andrew Prince]

Resuscitating this old thread, I cam across this test on ULSD and additives. Unfortunately it's an American test so the additives are not necessarily UK/Euro brands.
Here is the article. While it proves a point about un-improved ULSD being a poor lubricant and how much various additives improve the lubricity, it does not go on to test regular ULSD sold at the pump and what improvement, if any, additives make to the lubricity. A test with actual ULSD sold at the pump would be most meaningful for us.

Quite scary was the comment that testing of random samples of ULSD from the pump showed some batches had insufficient lubricity, contravening the minimum specs. The test was in the US so I wonder how our diesel consistency compares... For me this reinforces my preference to add 2stroke to "cheap" diesel, i.e. Tesco and the like.

 

[Dave2000]

Hmmm, I thought this was dead and buried? Anyway, it turns out that sulphur IS a lubricant! Everyone has his and her opinion and as I am not too hot on this tech stuff I emailed one of the fuel giants, it was confirmed that sulpur WAS used as a lubricant.....period!

So it still remains to be seen what effect the lower sulphur fuels has had on the longevity of the various pumps in use today. With regards to additives I can only say I use an injector cleaner additive once in awhile and that is it. I have seen no conclusive proof of adding ATF or otherwise to improve lubricity, on that basis I will just put in the regular pump stuff and call it done.

regards

Dave

 

[Andrew Prince]

Ok, Dave - apologies for flogging this dead horse but this sulphur issue is a common fallacy and because it's a Friday night I would challenge your source at the fuel company - was this really one of their chemists?
I assure you that sulphur was never added to fuel and is only there because of the naturally occurring sulphur in all crude oil.

Reference: http://en.wikipedia.org/wiki/Ultra-low-sulfur_diesel

Sulfur is not a lubricant in of itself, but it can combine with the nickel content in many metal alloys to form a low melting point eutectic alloy that can increase lubricity. The process used to reduce the sulfur also reduces the fuel's lubricating properties. Lubricity is a measure of the fuel's ability to lubricate and protect the various parts of the engine's fuel injection system from wear. The processing required to reduce sulfur to 15 ppm also removes naturally-occurring lubricity agents in diesel fuel. To manage this change ASTM International (formerly the American Society for Testing and Materials) adopted the lubricity specification defined in ASTM D975[12] for all diesel fuels and this standard went into effect January 1, 2005.[13] The D975 standard defines two USLD standards, Grade No. 2-D S15 (regular ULSD) and Grade No. 1-D S15 (a higher volatility fuel with a lower gelling temperature than regular ULSD).

For the sake of clarity, what this means is the sulphur compound in the diesel can bond with the nickel ions in the steel and aid fluid flow (lubrication) - image the teflon coating on your frying pan and an egg. The teflon isn't lubricating the egg but preventing it from sticking so that it can "flow" more easily around the pan.

Anyway, apologies again for the geek lecture At the end of the day it doesn't really matter - there seems to be some anecdotal evidence that some ULSD diesel might occasionally be deficient in lubricant additive. I think it's beyond debate that ULSD did not loom large when Mr T was doing his homework and designing the HD series of engines - up to the individual whether you want to invest/waste money on additives like 2 stroke

Cheers,

 

[Dave2000]

Hi Andrew, no apologies needed mate, IIRC it was a rep from Shell? I will try to find the email but it was way back when. I actually emailed them direct and then got passed onto the department that dealt with the tech stuff. Either way, as you said it is dead in the water now, if I come across the mail I will post it up.

Have a good weekend

regards

Dave

 

[Dave2000]

Found it! Yeh I know, don't I have better things to do a Friday night?

So I have simply copied the email as it run, the final paragraph is the what interests me:

ME

Hi, I recently made a comment on a forum which was worded pretty much as follows: 'I prefer to use the older style diesel in my old Landcruiser because I think the newer fuels have less sulphur which is an antiwear agent'.

A reply was made that 'sulphur is not a lubricant and it was the process of removing sulphur that reduced it's lubricity'.

I was under the impression that sulphur was a natural lubricant but had to be strictly controlled because it can also cause corrosion in the engine and was not good for the environment? I assume that reducing the sulphur shell and I assume other oil companies replaced the lubricity by using additives? The point in question is: Does or can sulphur reduce wear/friction within an engine?

Many thanks for taking the time to answer this question

regards

Dave


SHELL

Hi Dave,

Firstly, Sulfur is a chemical element which is one of the components
of a byproduct during crude oil distillation to produce Diesel. This
mostly relates to environmental concerns.

The importance of Sulfur is to protect the emissions control of the
engine. This property can also contribute to the lubricity of Diesel.
If the sulfur content is lower, it can affect lubricity thus;
additives are added to compensate for the loss.

Lubricity is a property that is important to the injector and pump
wear. Thus, relating the Sulfur and Lubricity with each other has an
effect on the wear/friction of the engine.

Hope this helps. Please let us know if you need further assistance.

Best regards,
Christine Enriquez
Technical Helpdesk

ME

Hi and thanks you for your reply, is Sulfur a lubricant in itself or do you need to add other chemicals to make it so? Everything else is clear in your email, thank you

regards

Dave

SHELL

Hi Dave,

Firstly, Sulfur is a chemical element which is one of the components
of a byproduct during crude oil distillation to produce Diesel. This
mostly relates to environmental concerns.

The importance of Sulfur is to protect the emissions control of the
engine. This property can also contribute to the lubricity of Diesel.
If the sulfur content is lower, it can affect lubricity thus;
additives are added to compensate for the loss.

Lubricity is a property that is important to the injector and pump
wear. Thus, relating the Sulfur and Lubricity with each other has an
effect on the wear/friction of the engine.

Hope this helps. Please let us know if you need further assistance.

Best regards,
Christine Enriquez
Technical Helpdesk

ME

I'm sorry; I think I am not wording my questions correctly. What I/we need to know is:

Is the compound Sulfur a lubricant i itself?

many thanks

regards

Dave


SHELL

Hi Dave,
Apologies for the late response. Do you mean if Sulfur acts as a “lubricant” in the fuel? If that is your question, then the answer is yes, since the Sulfur content has an effect on the lubricity property. Hope this helps. Just let us know if you need further assistance.
Best regards,
Christine

More fuel on the fire.......or is that diesel I smell?

regards

Dave

 

[Andrew Prince]

Thanks, Dave
The tech "expert" is being casual with the facts - "Sulfur is a chemical element which is one of the components
of a byproduct" - it's part of all crude oil and is part of the vast majority of crude oil derivatives unless removed beforehand (and it is removed by a hydro-desulphurisation process, which also breaks down the compounds that DO provide much of the lubricity in diesel)
Likewise, the sulphur playing a small part in aiding lubricity, as I described before, is very different from being a lubricant but I guess the respondent didn't get the "is sulphur a lubricant" part and mistook it for meaning does sulphur make a contribution to lubricity. I wonder what her answer would be to the question of whether sulphur removal simultaneously removes the main lubricant compounds in diesel, but sulphur is not one of those main lubricants (even if it does aid lubricity a small amount)?

Anyway, we're debating the finer points that aren't really relevant I'm pretty comfortable with what the answer is, so I'll bow out of the sulphur topic from here.

 

[Dave2000]

I also agree that this has gone as far as it can, it's great when you have all the facts....................ish

kindest regards

Dave

 

[Andrew Prince]

Yip, I think the only facts are ULSD in neat form lacks lubricity - and fuel manufacturers must add additives to improve the lubricity The fraidy-cats among us aren't sure that the cheapo diesel we buy always has the right amount of additives (with NO scientific basis for this suspicion) so we add 2stroke and hope that we're doing good.