Operation and maintenance manual

QSB4.5 and QSB6.7 Lubricating Oil Recommendations and Specifications
Section V - Maintenance Specifications Page V-11
CAUTION
An SAE 10W-30 designation on a product is a
viscosity designation only. This designation alone
does not imply that the product meets Cummins Inc.
requirements. Only 10W30 oils with diesel
performance credentials listed in table above can be
used in Cummins® engines if the reduced ambient
temperature indicated in chart above is observed.
The primary Cummins Inc. recommendation is for the use
of 15W-40 multigrade for normal operation at ambient
temperatures above -15°C [5°F]. The use of multigrade oil
reduces deposit formation, improves engine cranking in
low temperature conditions and increases engine
durability by maintaining lubrication during high
temperature operating conditions. Since multigrade oils
have been shown to provide approximately 30 percent
lower oil consumption, compared with monograde oils, it's
important to use multigrade oils to be certain your engine
will meet applicable emissions requirements. While the
preferred viscosity grade is 15W-40, lower viscosity
multigrades can be used in colder climates. See the
accompanying chart.
Oils meeting a 10W30 viscosity grade, must meet a
minimum High Temperature/High Shear viscosity of 3.5
cSt., and ring wear/liner wear requirements of Cummins®
and Mack™ tests. Thus, they can by used over a wider
temperature range than 10W30 oils meeting older API
performance classifications. As these oils will have
directionally thinner oil films than 15W-40 oils, top quality
Fleetguard® filters must be used above 20°C [70°F].
Some oil suppliers might claim better fuel economy for
these oils. Cummins Inc. can neither approve nor
disapprove any product not manufactured by Cummins
Inc. These claims are between the customer and oil
supplier. Obtain the oil supplier's commitment that the oil
will give satisfactory performance in Cummins® engines
or do not use the oil.
An example of the API service symbols are shown in the
accompanying illustration. The upper half of the symbol
displays the appropriate oil categories.
The center section identifies the SAE oil viscosity grade.