MACHINERY LUBRICATION- INDIA SEPTEMBER-OCTOBER 2019 | Page 9

MLI
OIL ANALYSIS AND
OTHER REPORTABLE
CONDITIONS WHAT IT
COULD MEAN WAYS IT CAN
CAUSE HIGH OIL
CONSUMPTION WAYS HIGH OIL
CONSUMPTION CAN
CAUSE IT WAYS IT CAN OCCUR
CONCURRENT WITH HIGH
OIL CONSUMPTION
Low base number/high
acid number High blow-by, water
contamination, distressed
base oil, high sulfur fuel Corrosion of piston-
ring-liner (PRL), piston
ring-pack deposits Low oil level
prematurely depletes
overbase detergents
and antioxidants High blow-by gas ingestion due
to poor compression/combustion
efficiency
High oil viscosity High soot load, wrong oil,
glycol in oil, hot oil, extended
oil drain, oil oxidation High ring float, piston
ring-pack deposits Fractional evaporative
light-end oil loss High blow-by (soot) due to
poor compression/combustion
efficiency
Low oil viscosity Fuel dilution, wrong oil, VI
improver shear Evaporative light-end oil
loss, PRL wear High soot load High blow-by, extended oil drain,
exhaust gas recirculation (EGR),
long idle, etc. High ring float from
elevated viscosity,
piston ring-pack
deposits, PRL wear Low oil level
concentrates soot High blow-by (soot) due to
poor compression/combustion
efficiency
Low soot dispersancy Water contamination, high
soot load, fuel dilution,
extended oil drain, coolant
leak Piston ring-pack
deposits Low oil level depletes
dispersant prematurely High blow-by (soot) due to
poor compression/combustion
efficiency, incomplete combustion
and blow-by (fuel dilution)
Water contamination Coolant leak, short intermittent
operation, cold temperature PRL corrosion Sludge and oxide
insolubles Extended oil drain, base oil
oxidation, poor dispersancy,
depleted detergency Piston ring-pack
deposits, PRL wear Fuel dilution High blow-by, PRL wear,
extended oil drain, injector
issues, overfueling/lugging PRL wear and blow-by,
premature base oil
oxidation (piston-ring
deposits) Incomplete combustion and
blow-by (fuel dilution)
Coolant (glycol)
contamination Coolant leaks from defective
seals, cavitation, corrosion,
damaged cooler core, head
gasket leak, etc. High ring float from
elevated viscosity, PRL
corrosion, PRL wear,
piston ring-pack deposits High blow-by gas ingestion due
to poor compression/combustion
efficiency
Dirty oil (silica)
and other solid
contaminants Dirty air induction, defective
oil filter, dirty fuel, dirty
new/backup oil, wear and
corrosion debris PRL abrasive wear
causes high oil
consumption
lubricant motion (transport) within the
ring-pack. This ring motion defines the
residence time of the lubricant in the
ring-pack, which in turn affects the rate
of lubricant degradation and where
deposits will form (see Figure 2). Ring-
pack temperatures can range from
195-340 degrees C.
Collectively, these conditions can
accelerate piston-ring-liner (PRL) wear,
impair combustion efficiency, increase
blow-by and reduce oil economy (more
oil consumption). One way this happens
Incomplete combustion and
blow-by (fuel dilution)
High blow-by and short
intermittent operation
Low oil level raises
sump temperature and
prematurely depletes
antioxidants
High oil consumption
carrying particles
causes excessive PRL
abrasive wear and
more particles
is through carbon jacking. In this
phenomenon, carbon buildup occurs in
the ring grooves (fed by soot and oil
degradation
products).
The
corresponding
ring
movement
restriction increases wear, blow-by and
oil consumption with the rhythm of the
piston.
Cylinder Wall Oil Evaporation
As much as 17 percent of total oil
consumption is associated with liner
wall evaporation. The more distorted
High blow-by gas ingestion
brings in induction air dirt and
fuel dirt
(out-of-round) and rough (surface
finish) the cylinder liner, the more oil
film that will remain on the liner after
the power stroke. High liner surface
temperatures (80-300 degrees C) will
cause a loss of this oil by misting and
evaporation. Light oil molecules are
more prone to evaporation. These light
molecules are the first to deplete, and
as a result, there is less evaporative loss
toward the end of the lubricant’s service
interval.
Not all oils of the same viscosity are
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