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Welcome To Mopar1973Man.Com LLC
We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features. Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.
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