5.16 Lubricity

Diesel fuel injection systems rely on the diesel fuel to prevent wear in moving parts. In limited cases,

some diesel fuel with very specific properties can have insufficient lubricating properties, which can lead

to excessive wear of fuel injectors and pumps. The primary properties of concern are low viscosity and

lack of lubricity. The minimum viscosity is controlled by ASTM D 975 and historically lubricity has been

provided by naturally occurring surface active materials. However, these natural lubricity agents can be

removed if severe hydrotreating processing is used. Hydroprocesses are used to reduce sulfur and

aromatics contents and with the phasing in of 15 ppm sulfur content diesel fuel beginning in 2006 in the

U.S., there is the potential for lubricity-related problems with fuel injection systems. It is important to note

that not all severely hydrotreated diesel fuel will have low lubricity because lubricity is affected by the

crude oil, processing severity, and blending of the fuel. Experience has shown that in 1991 in Sweden,

severe injector system wear occurred with ultra-low sulfur content diesel fuel. However, California’s

experience has indicated adequate lubricity performance can be achieved with its low sulfur diesel fuels if

a minimum SLBOCLE level of 3000 grams (g) is observed.

To assess the lubricity performance of diesel fuels, ASTM, ISO, and CEC have undertaken test programs

to develop laboratory bench tests. The resulting published test methods are ASTM D 6078 Test Method

for Evaluating Lubricity of Diesel Fuels by the Scuffing Load Ball-on-Cylinder Lubricity Evaluator, ASTM D

6079 Test Method for Evaluating Lubricity of Diesel Fuels by the High Frequency Reciprocating Rig

(HFRR), DIN/ISO 12156-1 Diesel Fuel-Measurement of Lubricity by HFRR, and CEC F-06-A-96

Measurement of Diesel Fuel Lubricity. The three HFRR test methods (D 6079, ISO 12156, and CEC

F-06-A-96) are very similar, but a number of small differences exist including the use of humidity

correction factors and rating photographs. Several studies have been conducted comparing the test

procedures among two types and with pump and vehicle tests. The correlation between the Scuffing

Load Ball-on-Cylinder Lubricity Evaluator (SLBOCLE) and the HFRR test methods is poor. Further, the

reproducibility of both bench test methods is large. Studies have also shown that the bench test

methods, particularly the HFRR, predict negligible benefits from an adequate level of lubricity additives

that provided acceptable durability in full scale equipment. As a result, excessive amounts of additive

have to be used to obtain a good bench test rating. Both bench test methods have shown better

correlation with pumps that have operated on diesel fuel that did not contain lubricity additives. Studies of

lubricity test methods are continuing.

Additives are commercially available that will restore lubricity lost due to refinery processing or improve

diesel fuels with poor lubricity. However, some of these additives have harmful side effects such as the

interaction of high concentrations of additive with the engine oil in in-line fuel injection pumps, which

causes fuel filter clogging and a marked reduction in pump efficiency. Another problem has been the

reaction with antifoaming additives and the deactivation of the defoamer performance. Thus, it is

important that the type and amount of additive does not result in harmful side effects.

A number of organizations have developed either diesel fuel lubricity specification limits or guidelines.

For the HFRR the wear scar diameter limits range from a maximum of 400 to 600 micrometers (?m) at 60

°C. For the SLBOCLE specification limits range from a minimum of 2800 g to a minimum of 3100 g.

ASTM is in the process of balloting a specification limit in ASTM D 975. ASTM believes that the inclusion

of a single fuel specification in the main table for Grade No. 2-D requires further research because 1) the

correlation of the data among the two test methods and the fuel injection equipment needs further

clarification, 2) both methods in their current form do not apply to all fuel-additive combinations, and 3)

the reproducibility values for both test methods are large. In the meantime, the following ASTM D 975

information may be of use and serve as a general guideline to fuel suppliers and users.

The following ASTM guidelines are generally accepted and may be used in the absence of a single test

method and a single fuel lubricity value:

a. Fuels having a SLBOCLE lubricity value below 2000 g might not prevent excessive wear in

injection equipment while fuels with values above 3100 g should provide sufficient lubricity in all

cases.

b. If HFFR at 60 °C is used, fuels with values above 600 ?m might not prevent excessive wear while

fuels with values below 450 ?m should provide sufficient lubricity in all cases.

c. More accurately, an industry-accepted long-term durability pump test, such as the ones used on

a test stand or in a vehicle, can be used to evaluate the lubricity of a diesel fuel. A poor result in

such a test indicates that the fuel has low lubricity and can cause excessive wear.

Now jump over to my HFRR testing page and review most of the fuel additives out there and see how they rank... 8|

http://mopar.mopar1973man.com/cummins/general/2-cycle-oil/hfrr/hfrr.htm

While your at it you might look at what a cetane booster does to BTU content too...

viewtopic.php?f=14&t=313

I wonder what the HFRR rating of older high sulfur content diesel fuel was, before low and ultra low sulfur fuels? This would be of interest to me just as a comparason of what is was then to what it is now. Harry

I recall reading 350 for #2 in '90 on some bodies parts counter sheet for the run up to the first part of 'those things stink' and some chemist told them that it was the sulphur. I notice that the smell is different on the ULSD. But the people in the offices are the direct representative of God, they can't be offended by smells that they don't like.keydl

Thanks Keydl. So I guess that at 128:1 with 2cycle that I'm sorta close, but at least below 500 maybe in the low 400's. Harry

  harry6oh said:

Thanks Keydl. So I guess that at 128:1 with 2cycle that I'm sorta close, but at least below 500 maybe in the low 400's. Harry

At 128:1 ratio I'm sure you meeting both standards (Gov't and Manufacture). So far I'm running close 50K miles with 2 cycle oil and no fuel system problems yet... :thumbsup

I think that a copy of the tests that thedieselplace did is here, 2cycle at 200:1 ( why that ratio? ) met the min spec with raw fuel.When the fuel is delivered the driver is supposed to add the material spec'ed by the brand so the fuel meets Fed spec. Now when adding lubricity to the fuel with 2cycle is it straight line addition, does it graph a loop or is it catalytic?. It takes at least 4 tests to really have a clue - a guess, double the guess, double agin and 10 times guess - if they graph straight you have a well founded guess that addition will work wonders. If it is catalytic the graph is a point.That is the reason that I advocate that if someone is going to start with 2cycle on an unmolested engine and they pick up fuel tickets with the odometer reading on them that they start at 1/4 the currant recommend for the first 1k miles and increasing for the next 1k miles followed by 1k at 1 oz per gallon.The results of adding a gallon of WEO were not as expected, using the numbers on the pump the mileage was the same but when th3e extra gallon was added the mileage was down. I run Rotella syn, it does not burn well when you add it to a hot fire, but it does eventually add a few BTUsSome places that would take a week to dokeydl

So, your using WEO for a fuel lubricity additive? And, aren't synthetic oils supposed to be more resistant to burning? Thats why they are better for our turbos, the oil dosen't coke up as bad inside due to the heat its subjected to, especially after shutting the engine down. Harry

Like I got after a guy over at TDG.com tonight...

Then is engine oils are not meant to be burned really... There is other components, chemicals, etc that just don't burn right... Give you an idea... Here is a WEO/WMO heater...

Brand new burner never used.

24 hours later...

To clean up the mess...

Now as soon as someone can find me a guy running the quarter mile, dyno, sled pull perofessionally and is doing better than #2 diesel fuel using WEO/WMO or WVO I start listening... But at this time there isn't a single professional racer/driver that is using WEO/WMO or WVO as a fuel. Maybe because its not a fuel... :confused

Well the gallon of Rotella syn that I ran through the tank made 0 difference in the cost, add the gallon to the pump reading and the fuel mileage dropped.Dollars for miles within a quarter. But the drain oil was free I will go back to painting fences with it.keydl

Wow, what a mess, that burnt coked stuff is scary looking. Looks like the inside of a clogged catalytic converter on a gas engine vehicle that has a oil burning/consumption problem. Harry

This is why I've been studing fuel additives and fuel relaed stuff for over 2 years... So far I've been right on the ball with most stuff... But as for cheating the system by using waste oils just ain't going to cut it. The whole factor of BTU content, lubricity, derbris content, ash content, burn characteristics, etc are all balance and will not proform as good as good ol' #2 fuel. So it any case its a WASTEFUL practice because you going to need much more fuel...

Because Cummins tolerates WEO, I expected to get the same mileage - the drain oil to substitute for a gallon of #2. That is the way that it worked in the mid '70's relocating scrap with a 350 small cam Cummins and a MD Toroflow. Much less crap in the drain oil.O well it subs for $24 paint if you want black.keydl

Don't get me wrong Keydl the weo/WMO can be used in a Cummins as long as you stick to a few rules it will consume it just fine... * WEO/WMO is filrered down to 2-5 mcirons before use. Only engine oil to be burned. Prefered only petroluem oils.*Dose doesn't exceed 5% by volume tops. (1.75 Gallons) But Cummins Centinel use ways less... I would stick to 1-2 quart tops and you would be able to burn without the loss...

When I burn regular 2stroke mixed at 50:1in my chainsaw/blower/weedwacker=they smoke a little. When I burn 2cycle tcw3 at 50:1 in the same equipment=no smoke, and they seem to run better. Just an observation. Harry

I manage a couple of lawn crews, the keep the weeds beat back on a couple places for the parking and observation on the crews.O of the things I do is give up 5 gallon of mix gas when they work, the 2cycle is synthetic 100:1 listed oh the label. It is all mixed at 100:1 and has caused no problems, even in an old chainsaw that wanted 16:1 mix ( cast in the housing ), it was free because it used spark plugs - 2-3 a working day - had since his dad took it to the woods. Would not hit on ether, but a new plug and some cranking with a drill and it started, serviced the points and it started easy and ran well. Been working at 100:1 since 2000.The owner is willing to buy 5 gallon a working day and the 2cycle on the job should be just under 2 gallon so all that is not used goes in a vehicle tank - have not heard of any problems, not sure any of the crew would make the connection if there were any problems. The stuff also feeds the 4stroke motors with no problem, but I got one to run on kerosene, my mistake.keydl