Oil viscosity is very important for a diesel engine or a diesel generator. But how to judge the oil viscosity is good or not? Read this article and you will learn a lot.
Cummins generator engine oil viscosity
Viscosity is
a measure of the resistance to flow offered when one layer of oil molecules
move relative to an adjacent layer. This resistance comes from the friction
generated by the oil molecules as they move past each other. This shearing
action occurs constantly in the oil films lubricating all moving parts of an
engine.
The
viscosity characteristics of all fluids are affected by temperature.
Multi-grade oil viscosity tend to be less sensitive to temperature changes
because of the addition of viscosity improvers in their formulation. The
viscosity of multi-grade oils is also a function of their rate of shear, or the
relative speed of moving parts. The lower the relative speed, the greater the
apparent viscosity of most multi-grade oils.
Most of the wear
an engine ordinarily experiences occurs at initial startup in some applications
before oil has time to fully circulate. The correctly formulated multi-grade
oil is the ideal engine lubricant for a Cummins engine. Relatively thin oil is
available tor rapid lubrication and easy cranking while starting.
Oil Viscosity and Engine Performance
The
selection of oil of the correct viscosity is extremely important for optimum
performance and for maximum engine life. If the oil is too viscous, engine drag
is increased with the following effects:
● Engine is
difficult to start
● Engine
power output is reduced
● Engine
cooling is reduced
● Internal
wear is increased
● Engine
parts run hotter
● Fuel
consumption is increased.
If the oil
viscosity is too low, the engine experiences:
● Increased
wear from metal-to-metal contact
● Increased
oil consumption and leakage
● Increased
engine noise
Some oil
suppliers might claim better fuel economy for the lower viscosity oils, Lower
viscosity results in tower oil film thickness. Therefore, Cummins Inc. has
required that all multi-viscosity 30 weight (xW30) oils registered under CES
20078 (API CI-4) must meet the minimum High Temperature / High Shear viscosity
of 3.5 cSt. These can be used over a wider temperature range than other 10W30
or 5W30 oils. As these oils will have directionally thinner oil films than
15W40 oils, top quality Fleetguard filters must be used above 20°C [70°FJ. See
Figure l for viscosity recommendations.
As CCEC can
neither approve nor disapprove any product not manufactured by CCEC,
these claims
are between the customer and the oil supplier. Obtain the oil supplier's
commitment that the oil will give satisfactory performance in Cummins engines,
or do not use the oil.
Viscosity
Recommendations
CCEC
recommends the use of multi-grade lubricating oils with viscosity grades shown
in Figure 1 for the ambient temperatures indicated. Only the preferred oil
grades are shown in the figure.
If
mono-grade oils are substituted for multi-grade oils in the areas where
multi-grades are not currently available, shortened drain intervals might be
required, as determined by close monitoring of the oil condition with scheduled
oil sampling. Use of mono-grade oils can affect engine oil control.
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