Prove to me that you NEED a lubricating additive. I expect this problem to have been solved by the fuel blenders.

To me it was significant that someone who does oil analysis for a living thought it was a good idea...and it's really the only case where he recommends any sort of additive.

To quote him: "There is one component that I firmly believe in, and that is lubricity additives. In the absence of sulfur there is little lubricating value in ULSD fuel. This is especially important in older sleeve metering and scroll type injection pumps. In addition, cold flow improvers are equally important in severe cold."

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Do we know that refiners aren't blending additives into their fuel? It's just that I have 412K miles on the 190DT and have never used a "lubricity additive". It's hard to imagine how much further I could take this bucket of rust if I had only invested in a few little bottles of lawnmower oil years ago.

You'd have one of dem million mile Benzes!

Seriously...yours could a statistical outier. And you're drawing your conclusion from a sample size of one. But an oil analysis lab is going to have a large and diverse sample, from which they can draw reasonable conclusions about the value of added lubricity.

But certainly congrats on that many miles.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

It's difficult to know for sure if adding any type of lube to the fuel is beneficial, my '95 E300 has over 400000 miles on it and the only thing I have ever added to the fuel was "Power Service"during the 8 winter months to prevent gelling of the fuel in this terrible frozen climate that I live in.

Never used it in my 300CD or my 300TDT either. I guess I do a lot of outlying. No doubt I buy fuel from the only dealers who care enough to blend their fuel properly.

Since I'm an outlier, you must have hundreds, maybe thousands, of engines that have been ruined, totally ruined, by the lack of fuel lubricity. Yet these pages are all but devoid of examples of people replacing failed injection pumps. Show me just ten of those failed IP's, with evidence that the problem is excessive wear, and I'm convinced.

As I indicated above, my conclusion is that 2 stroke oil additive is cheap insurance. I don't know if is necessary but it can't hurt.

I believe the following to be factual

- sulfur is a good lubricant
- fuel is used as the primary lubrication media of the injector pump
- after the 617 was designed sulfur has been all but eliminated from available fuels
- fuel lubricity is severely reduced from design specifications
- fuel additives can significantly increase the lubricity of ULSD
- at least one blind study (now somewhat dated) documents in detail results of lubricity testing

Here is a link to that study - http://www.jatonkam35s.com/DeuceTechnicalManuals/Diesel_fuel_additive_test.pdf

I've selected 2 stroke oil for cost, convenience, apparent effectiveness and availability.

Maybe it's not needed, but for the cost and inconvenience of replacing an injector pump if it is, I'll keep on until something better comes along or blind testing on actual injector pumps shows it's not needed....like I said, cheap insurance.

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Current Stable

• 380SL (diesel)
• Corvette C5
• Manx
• Baja Bug
• F350 Powerstroke
• Auburn Boattail Speedster replica

The old Lubricity test...it's the reason I chose XPD.

Got it because I hope it will quite down my 603.
The thing sounds like a little cummins (which is actually starting to grow on me)

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

The problem is that the study is totally worthless. Why? Because it starts with unaditized Diesel. You can't buy that fuel, unless you go directly to a refiner and take a sample before it's conditioned for sale. I think that particular study was the corporate product of Optilube. Some of the results are simply unbelievable, as in used motor oil (high sulfur, BTW) REDUCING lubricity.

Here's a study from Chevron that's a little more technical, and I think, reliable:

https://www.chevron.com/-/media/chevron/operations/documents/diesel-fuel-tech-review.pdf

Important quotes:

1) "Lubricity enhancing compounds are naturally present in diesel fuel derived from petroleum crude by distillation. They can be altered or changed by hydrotreating, the process used to reduce sulfur and aromatic contents. However, lowering sulfur or aromatics, per se, does not necessarily lower fuel lubricity"

and

2) "There are three ways to evaluate the lubricity of a fuel. In order of decreasing long-term and increasing simplicity, they are:

•Vehicle testing
• Fuel injection equipment bench tests
• Laboratory lubricity testing

Vehicle tests require a lot of fuel, time, and effort. They are usually reserved for basic studies of fuel performance. Fuel injection equipment bench tests, such as ASTM D 6898, require 50 to 100 gallons samples of fuel and 500 to 1,000 hours of operating time. Both ASTM D 6078 and D 6079 are relatively quick, inexpensive, and easy to perform..."

And

"The HFRR and the SLBOCLE tests can indicate that fuels treated with an effective lubricity additive have poor lubricity, while the more accurate fuel injection equipment bench test rates them acceptable"

In other words, quick, cheap laboratory testing as in the Optilube study may not be indicative of wear experience in actual pumps. This is important to know, because HFRR testing is the basis of all the woeful hand wringing over fuel lubricity.

Soooo...it would appear that fuel blenders are aware of the problem, and know how to address it. My expectation is that pump fuel is fine, simply because no refiner would want the responsibility of ruining millions of very expensive engines. I come back to my challenge: show me ten IP's that have been destroyed by poor fuel lubricity, and I'll start using lawnmower oil. If nobody raises their hands, QED.

The problem is that the study is totally worthless. Why? Because it starts with unaditized Diesel. You can't buy that fuel, unless you go directly to a refiner and take a sample before it's conditioned for sale. I think that particular study was the corporate product of Optilube. Some of the results are simply unbelievable, as in used motor oil (high sulfur, BTW) REDUCING lubricity.

Here's a study from Chevron that's a little more technical, and I think, reliable:

https://www.chevron.com/-/media/chevron/operations/documents/diesel-fuel-tech-review.pdf

Important quotes:

1) "Lubricity enhancing compounds are naturally present in diesel fuel derived from petroleum crude by distillation. They can be altered or changed by hydrotreating, the process used to reduce sulfur and aromatic contents. However, lowering sulfur or aromatics, per se, does not necessarily lower fuel lubricity"

and

2) "There are three ways to evaluate the lubricity of a fuel. In order of decreasing long-term and increasing simplicity, they are:

•Vehicle testing
• Fuel injection equipment bench tests
• Laboratory lubricity testing

Vehicle tests require a lot of fuel, time, and effort. They are usually reserved for basic studies of fuel performance. Fuel injection equipment bench tests, such as ASTM D 6898, require 50 to 100 gallons samples of fuel and 500 to 1,000 hours of operating time. Both ASTM D 6078 and D 6079 are relatively quick, inexpensive, and easy to perform..."

And

"The HFRR and the SLBOCLE tests can indicate that fuels treated with an effective lubricity additive have poor lubricity, while the more accurate fuel injection equipment bench test rates them acceptable"

In other words, quick, cheap laboratory testing as in the Optilube study may not be indicative of wear experience in actual pumps. This is important to know, because HFRR testing is the basis of all the woeful hand wringing over fuel lubricity.

Soooo...it would appear that fuel blenders are aware of the problem, and know how to address it. My expectation is that pump fuel is fine, simply because no refiner would want the responsibility of ruining millions of very expensive engines. I come back to my challenge: show me ten IP's that have been destroyed by poor fuel lubricity, and I'll start using lawnmower oil. If nobody raises their hands, QED.

So the technical article basically said that diesel fuel already has decent lubricity. welp I guess facts don't care about our feelings.
I also like how the article says in the most polite manner that many additives are potentially snake oil. -A large number of aftermarket additive products are available to meet these real or perceived needs. Some are aggressively marketed with testimonials and bold performance
claims that seem “too good to be true.” As with any purchase, it is wise to remember the
advice, caveat emptor, “let the buyer beware"

Even Chevron admits that nobody is really testing the effectiveness of all the additives out there.

__________________
1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

Yes.....

My friend who has worked at Bosch since 1968 says, "Use any top tier diesel fuel and you should be fine." He says Bosch tests diesel fuel from different stations and there is a difference....stick with top tier such as Philips, Exxon/Mobil, Conoco, Shell, Sunoco, etc.

I think the only MB approved fuel additive is Biopor for Algae/microbial control. He said Bosch and MB do not recommend adding anything else to the fuel tank.

The reasoning is that if you are using top tier fuels, they will be properly refined with necessary additives and ready for use. Adding any other additives just isn't necessary.

Diesel engines are robust by nature so additives added by the operator probably do not hurt but they really do not enhance the fuel in any meaningful way.

In short, save your money. Put it into buying the best quality parts for your next repair.

__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991

Simply sounds like there's a diversity of opinion among those who are genuinely experts in the field (not any of us, from what I can tell)...no crime in that. But for people who do oil analysis for a living to claim that it's beneficial should be reason enough to err on the side of caution...especially since it's such a minimal expense and takes so little effort.

__________________
14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 157k miles
06 E320 CDI "Rutherford", Black on Tan, 175k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 144k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 70k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Again, you see zero failures of Mercedes IP pumps related to lubricity. None. Not one. The only place you may find a pump failure of any sort is on the veggie oil or racing forums, and those will be for different reasons. So we have millions of miles of experience, most of us with no additives, and no proof that there is an actual problem.

Edit: Nevermind, I really need more coffee. Wow.

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617 swapped Toyota Pickup, 22-24 MPG, 50k miles on swap