ENGINE OILS EFFICIENCY CRITERIA: SELECTION

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Leimeter Tibor

• ENGINE OILS EFFICIENCY CRITERIA SELECTION BASIS

2007
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Factors in the efficacy and service life of
engine lubricants
Creation
Storage

• Type and quality of fuel
• Combination of additives
• Stability of performance characteristics
• Thermal stability
• Thermooxidative stability
• Detergent and dispergation properties
• Anti-corrosion properties
• Lubricating efficacy

Application
Engine oil quality
Replacement
Durability reduction
Exploitation period
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Causes of changes in basic engine lubricant
parameters
Name of change Name of change
Cause Cause
Increased viscosity Increased viscosity
Oxidation Oxidation
Polycondensation Polycondensation
Products of incomplete fuel combustion Products of incomplete fuel combustion
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Main changes in in-service lubricants, based on
infrared spectral analysis
Polycondensation results from an oxidation chain
reaction, i.e., loss of the additives
antioxidative and neutralizing action
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Effect of basestock on engine lubricant
thermooxidative stability
1 original lubricant, 2 oxidized (3 hours)
lubricant
The accumulation of polycondensate products of
aging is determined by calorimetric and
colorimetric methods, with calculation of the
depletion index based on the ratio of
calorimetric curve peaks
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Limit of alkalinity as a criterion of engine
lubricant efficacy
1 viscosity 2 acidity, 3 optical density
The limiting (minimum) base number value depends
on the composition of the additives package,
especially the number of active centers in the
additives
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Effect of the main components of additives
packages on the thermooxidative stability of
engine lubricants
Composite index - A
A ? (??Zn)/(??SABP)b
Alkaline components Ca Calcium Base
number Zn Zinc Acidic components AN Acidity
number S Sulfur P Phosphorus AA Active
agent sulfonates
Base number
Determined by potentiometric titration
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Dynamics of change in in-service engine lubricant
indicators
1 conductivity, 2 base number, 3 acidity
number, 4 - viscosity
I. Effective functioning of lubricant, II.
Lubricant replacement interval, III. Rapid aging
of lubricant and possible engine breakdown
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Effect of colloid-chemical structure of additives
on their neutralizing action

• Speed of reaction or neutralizing effect (V1V2)
• Total number of base centers (N)
• Base centers that undergo a neutralization
  reaction easily (N1)
• Base centers that undergo a neutralization
  reaction with difficulty (N2)
• Products of thermochemical transformations of
  lubricant (??)
• Products of fuel combustion (?n)
• Chemical reactivity coefficient of additive (?)

1. Sulfonate primarily colloidal neutralization
   (solubilization)
2. Phenolate chemical neutralization
3. Salicylate chemical neutralization

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Effective alkalinity, an informative indicator
for fresh and in-service engine lubricants

• Causes of loss of lubricants neutralizing
  efficacy
• Quantity of additives expended on neutralization
• Of strong acids (fuel combustion)
• Of weak acids (products of aging of lubricant)
• Quantity of additives expended on other functions
• Detergent action
• Dispergation
• Thermal decay and burn-off

Neutralization of organic acid by engine
lubricant 1 fresh, 2 - in-service
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Determination of the remaining service life of
engine lubricants
1 ?-8?, 2 SF/CC, 3 SJ/CF-4
1 hour of oxidation of a lubricant under
high-temperature catalytic oxidation conditions
is equivalent to 30 engine hours on an engine
lubricant testing device.
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Prediction of efficacy and service life of engine
lubricants under real use conditions
Engine oils efficiency prognosis
Determination of engine oil efficiency in real
conditions
Engine oil Predicted in-engine service life Predicted in-engine service life
Engine oil Gasoline, limit in thousands kmDiesel, limit in engine hours Gasoline, limit in thousands kmDiesel, limit in engine hours
?-8? 7 360
SF/CC 15 700
SJ/CF-4 18 800
Newly developed 15 750
??? Method correlation (1hour of oxidation) with
in-engine working period of motor oil
Type of engine Type of engine
gasoline, gasoline,
km traveled km traveled
API SF/CC Lubricant manufacturers
recommendation about 14,000 km traveled
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• Thank you for attention!