I've seen the same phenomenon with acidic corrosion rates on various steels and stainless steels. Sulphuric acid is one example. In most cases, the 98% sulfuric acid is far less corrosive than 50% sulfuric acid, and temperature makes a huge difference in corrosion rates for the same concentration of acid.

The temperature issue makes me wonder if the ball-scarring test is run at a temperature that is representative of what our injectors run at. If not, then even the data we have may not be meaningful depending upon the temperature at which the test was run.

 

Here's the response I received a few mooments ago from Mr. Westbrook. What it means is that some data does in fact exist, but he cannot share it with "the public".



Mr. Cleveland,

I appreciate your taking the time to send this message to me.

Unfortunately, I do not have any specific data that I am able to share with you.

Regards.

Steve Westbrook
Southwest Research InstituteÒ
PO Drawer 28510
6220 Culebra Road
San Antonio, Texas 78228

Voice: 210.522.3185
Cell: 210.315.3082
Fax: 210.522.3270
swestbrook@swri.org

 

I would hope that the tests are done at temperatures that replicate what the injectors are exposed to (at least the internal parts that are not directly exposed to the flame front and have critical lubrication requirements) because diesel viscosity is negatively correlated to temperature (as fuel temperature increase, viscosity decreases). You bring up a great point Pete!

 

i like what it says on the back label of marvel mysterious oil ( does not conform to thr ultra low sulfur requirement) my 1.5 cents

 

Well, now...this is interesting. I went to the Southwest Research Institute (SRI) and did some reading. Doing some reading, I found that the lubricity tests have been standardized as American Society for Testing and Materials (ASTM) D 6078. This is from the SRI site...read the Note at the bottom.



This took me to Chevron's website which gave some more info:

"Lubricity There is no doubt that lubricity is an important property of diesel fuel performance. A single tankful of fuel with extremely low lubricity can cause a fuel pump to fail catastrophically. Setting a lubricity requirement to prevent catastrophic failure is relatively easy; setting a requirement to avoid excessive fuel system wear is much harder. There are three ways to evaluate the lubricity of a fuel. In order of decreasing accuracy and increasing simplicity, they are:

<table border="0" cellpadding="0" cellspacing="0" height="48" width="400"> <tbody><tr> <td align="left" valign="top" width="12"></td> <td align="left" valign="top">A vehicle test</td> </tr> <tr> <td align="left" valign="top" width="12"></td> <td align="left" valign="top">A fuel injection equipment bench test</td> </tr> <tr> <td align="left" valign="top" width="12"></td> <td align="left" valign="top">A laboratory lubricity test</td> </tr> </tbody></table>
Vehicle tests require a lot of fuel and a lot of time and effort. They are usually reserved for basic studies of fuel performance. Fuel injection equipment bench tests, such as those designed by Bosch and Stanadyne, require 50 to 100 gallons of sample and 500 to 1000 hours of operating time. Since these tests have not been standardized, the criteria for a pass are not well defined.

Two laboratory lubricity tests have recently been standardized by ASTM: the Scuffing Load Ball-On-Cylinder Lubricity Evaluator method (SLBOCLE) and the High-Frequency Reciprocating Rig method (HFRR).These tests are relatively quick, inexpensive, and easy to perform.

A lot of work has been done in the past few years to correlate these laboratory tests with field performance. Some SLBOCLE studies indicate that fuels with values below 2,000 g usually will cause accelerated wear in rotary-type fuel injection pumps, and fuels with values above 2,800 g usually will perform satisfactorily. It should be noted that the SLBOCLE test 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.

Some HFRR studies indicate that fuels with up to 450-micron wear scar diameters at 60°C, 140F (380-micron at 25°C, 77F) will perform satisfactorily in all fuel injection equipment. However, other studies show that some fuels and fuel/additive combinations with values above this level still do not cause excessive wear." (bolded by me)

So it appears that temperature is at least considered to some extent...Though this whole search has now taken me to where I want to see vehicle testing results or some bench test results (due to their higher levels of accuracy). Finally, I'd like to make note of this quote:

"The Fuel Injection Equipment (FIE) manufacturers have adopted the use of the HFRR (ISO 12156-2:1998), and recommend that all diesel fuel meet a limit of 460 micron maximum Wear Scar Diameter (WSD). For the HFRR, a lower wear scar indicates better lubricity."

From the earlier post, these are the additives that meet the FIE recommendations:

 

Great info, Neal. Thanks for taking the time to search this out. I gues even though teh testing temperature is not at engine temps, at least it seems to be correlated with performance at engine temps, which is at least a good approximation for reality.

I know that once we're running bioD, that additives are reportedly "not necessary", but if the OptiLube drops the lubricity value of untreated diesel by roughly 30%, what would happen if you use the OptiLube with bioD in combination? Guess what.... I'm getting ready to run the OptiLube trial with my engine while simultaneously running B20.

I just ordered enough Opti to run through at least 10 tanks of fuel. Although I will not be measuring scarring on my injector internals, or running my own HFFR testing with my additive-enhanced bioBlend, I'll at least get a chance to evaluate mileage issues.

 

Since reading your post Pete, I have been digging deep to find anything that I could honestly call "documentation" concerning OD'ing fuel additives and negative consequences of OD'ing additives. I found lots of SAE papers with titles that imply they may have info to make the case, but they run $11 each. So I started pounding the military research documents (public domain) for testing results. Now here is a study titled:

"Fuel Lubricity Requirements for Diesel Engines"
INTERIM REPORT BFLRF No. 270

I perused it last night and found some info which certainly imply that following manufacturers recommended dosage (or perhaps even less than their recommended dosage) is what lubricity additive users should be looking at, for cost effectiveness. Now these tests were performed using Jet-A and Stanadyne pumps...so strictly speaking, they don't apply to PSD. But I would argue there are implications from this study.

One of fuel lubricant additives, had a manufacturer recommended dosage of 15 PPM. Here were the results:

dosage (PPM)/wear scar diameter (mm)

15/0.55
80/0.52
150/0.50
300/0.48

I would conclude that the lower dosage (recommended 15PPM) is the most cost effective dosage by far (a 2000% increase in lubrication additive dosage lead to only a 13% decrease in wear).

Also, they tested motor oil and gear oil as an additive (stated to be common practice by field personnel). They found any addition of motor oil or gear oil actually increased wear of fuel injection systems. In order of detrimental effect of gear oil or motor oil as a lubrication additive were:

80-90W gear oil
15-40W motor oil
10W oil

All of these caused the wear rates to increase when compared to straight fuel!

So maybe, just maybe, the fuel additive manufacturers dosage rate is built on science and if they have a bias it would be to higher than needed dosage (we use it faster, thus having to buy more).

 

I use the Diesel Kleen....or sometimes the Stana-dyne....or sometime Lucas.

Mostly use the Diesel Kleen as many others on this site do.

Some of these guys really do seem to "pick apart" some things.

 

Great info, Neal. Thanks for taking the time to dig in so deeply on this. Puts a few things to rest in my mind... like not worrying too much about overdosing as long as I can verify cost-effective mileage improvements to go along with it.... and avoiding the use of oil as an additive (or even more.... as a means of disposal of used motor oil).