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When requesting an oil analysis, always state the type of oil used as well as the time (number of hours) the oil
charge has been in service, and the engine specific oil consumption. We recommend the following properties are
checked:
- Viscosity
- TBN / TAN
- Oxidation / Nitration
- Water content
4. INTERPRETATION OF RESULTS
Oil degrades throughout its useful life due to oxidation, loss of effectiveness of the additives, and pollution by
combustion products, fuel, water or solids. This can be checked by reviewing the evolution of the periodical test
results.
Those analyses serve to check the oil contamination levels and to detect potential ill performance of oil. The most
significant test results may be interpreted in the following manner:
Viscosity
-
Oil viscosity is a very important feature, since it gives an idea of the working conditions of the oil that coats the
bearings with a lubricating film ensuring the lowest friction and leakage.
An increase in oil viscosity is generally attributable to the presence of oxidation products, dirt, insoluble
substances or wear elements.
Generally, the established oil change frequency prevents reaching the point where oil can no longer accept any
increase in contaminants.
TBN
-
It is the function of the alkaline additives contained in oil to neutralize the acidic products that develop during
combustion (mainly strong sulfuric and nitric acids) as well as weak organic acids resulting from oil oxidation
through aging.
TBN is a measure of the oil capacity to neutralize strong acids produced by the fuel combustion. It does not
measure the oil alkalinity, but the alkaline reserve of oil or its acid-neutralizing capacity.
A sharp fall of the TBN may occur due to a low consumption of oil, the use of a fuel rich in sulfur or a small
volume of the oil pan. Oil with a low TBN does not have enough capacity to neutralize the acids which corrode the
engine parts.
TAN
-
By measuring the oil acidity, it is possible to prejudge and determine the quantity of products of an acidic nature
contained in the oil. Such acidic products may originate both in the natural oxidation of oil and in its contamination
by sulfur compounds or halogen acids formed during combustion.
Chlorine
-
Halogenated compounds, if present in the form of acidic components, may prove very harmful to the engine.
Given their chemical nature, acids of this type of elements are very aggressive, attack almost all the metallic
components of an engine and shorten the working life of lube oil by destroying its reserve of additives.
PRODUCT INFORMATION
IO-G-M-25-001e
GAS-FUELED ENGINE OIL SERVICING INSTRUCTIONS
- Insoluble substances
- Metals
- Chlorine
- Observations
5.2.2
INDEX
DATE
G
January 2015
O&M_2.002211.810_A_10_2016
Dep.2
2/4
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