FUELS AND OILS
the hydraulic oil based on the FTIR results.”
TOTAL adds: “As such, on receipt of an oil
analysis report, many Reliability Engineers (RE)
or Maintenance Professionals make a call that
the lubricant health is satisfactory based on low
wear metals, stable viscosity and of course, the
ISO cleanliness code. The decision to extend the
oil past the oils ‘use by date’ is not based on a
holistic picture as the health of the lubricant in
this instance, cannot be based on those three
indicators.”
By this, maintenance teams and reliability
engineers review the oil analysis reports placing a
large emphasis on cleanliness results. “If the ISO
cleanliness results are at an acceptable code,
then the call to extend the oil is made. In some
instances, the hydraulic oil type selected by the
company may invariably be a standard mineral
hydraulic oil where some OEM’s and lubricant
companies would only suggest a 2,000 hour oil
drain interval. In some instances, companies
have been known to extend the ODI of large
hydraulic excavator systems well past the
capability of the hydraulic lubricant with the
decision made based on viscosity and
cleanliness of the lubricant. This approach, whilst
initially leading to reduced oil consumption
savings, does not take into cognisance the actual
health of the oil which in time will lead to
equipment issues resulting in increased
maintenance activities and operational cost. A
very important test measure not included as a
standard measure in routine analysis of hydraulic
oil samples is anti-oxidant content.”
When oils are exposed to the process of
oxidation, oxidative products are formed.
“Increases in oxidation could be as a result of
excessive operating temperatures or even from a
process known as ‘microdieseling’ which occurs
when entrained air bubbles implode when being
passed through high pressure zones within the
system. This results in very high localised
temperatures of the oil resulting in oxidative by-
products being formed.”
Lubricants contain anti-oxidants to combat the
process of oxidation but additives are sacrificial in
nature and ultimately get “used up”. When the
anti-oxidants within the lubricant gets too low,
then oxidation of the oil accelerates. “This,
together with an ineffectual method to remove
these oxidative by-products, ultimately leads to
varnish formation. These varnish deposits will
tend to drop out of solution and at the areas that
are coolest in the hydraulic or turbine system
thus leading to equipment unreliability, for
example, sticking of servo valves. The formation
of varnish does not happen overnight but rather is
an accumulation of continued over-extension of
the hydraulic oil, sometimes taking more than 5
years before the presence of varnish within the
hydraulic system becomes apparent.”
Test results from routine used oil analysis do
1,000 HRS
Meet the Cummins Engine that
Ran 1,000 hours with the Same Oil
not detect the level or anti-oxidants in the oil and
cannot determine potential formation of varnish.
Similarly, routine used oil analysis cannot be
used as the main justification for extending oil
drain periods. “In the case of hydraulic systems
using a standard hydraulic oil, it is important for
maintenance professionals to liaise with the
laboratory to include other tests. As a minimum,
Acid Number (AN) or Total Acid Number (TAN)
must be included in the routine suite of tests. In
addition, at 2000 hours operating time on oil and
every subsequent 1000 operating hours on the
oil thereafter, tests to confirm anti-oxidant levels
left in the lubricant should be carried out in order
to determine the overall health of the lubricant.
By closely monitoring physical and chemical
characteristics, a call can be made that the oil is
at or nearing the end of its useful life. This can be
determined by closely monitoring any increasing
trend in TAN which is also likely to be
accompanied by very small incremental increases
in viscosity. This trend, together with decreasing
anti-oxidant levels in the oil means that the
hydraulic oil must be replaced.”
In addition and as a supplement to the above,
laboratories can perform Membrane Patch
Colorimetry (MPC). Here, a set volume of oil is
passed through a filter membrane, also referred
to as a patch. The patch is then compared
against known reference patches and a number
assigned to the patch. The higher the assigned
That’s right – approved for 1,000 hours of operation,
with no oil change and no lubrication-related
downtime. In fact, the oil is nearly ageless, providing
the same asset protection at 1,000 hours as the day
it was added. That’s four times longer than the
OEM-recommended interval for this engine.
Cummins recently approved LE’s Monolec Ultra®
Engine Oil (8800) as a
1,000-hour-drain-interval,
long-service engine oil.
How’d we do it?
By implementing these two
simple solutions:
• Xamine™ Oil Analysis
• Monolec Ultra® Engine Oil
Read more about our engine
oils and customer successes at
http://www.le-international.com/testimonials.php
and then contact us to get started.
+44 118 930 4321 | [email protected]
L UB
UBRICATION
U
B R I C A TI
T I O N E N
NGINEERS
G I NEE
E R S
I NTERNATIONAL L TD .