ENGINE OILS EFFICIENCY CRITERIA: SELECTION & BASIS Leimeter Tibor 2007

Factors in the efficacy and service life of engine lubricants 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 Storage Application Replace ment Durability reduction Engine oil quality Creation Exploitation period

Causes of changes in basic engine lubricant parameters Name of change Cause Increased viscosity Oxidation Polycondensation Products of incomplete fuel combustion

Main changes in in-service lubricants, based on infrared spectral analysis Oxidation (acidity number) Depletion range of additives (loss of performance attributes) Polycondensation (viscosity) Polycondensation results from an oxidation chain reaction, i.e., loss of the additives’ antioxidative and neutralizing action

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

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

Effect of the main components of additives packages on the thermooxidative stability of engine lubricants A  [(Са+Zn)/(Кч+S+AB+P)] 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 Composite index - A

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 Время работы масла Показатели IIII II

Effect of colloid-chemical structure of additives on their neutralizing action 1.Sulfonate – primarily colloidal neutralization (solubilization) 2.Phenolate – chemical neutralization 3.Salicylate – chemical neutralization Speed of reaction or neutralizing effect (V1;V2) 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 (Со) Products of fuel combustion (Сn) Chemical reactivity coefficient of additive (К)

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

Determination of the remaining service life of engine lubricants 1 – М-8В, 2 – SF/CC, 3 – SJ/CF-4 ОкислениеМоторный стенд hour of oxidation of a lubricant under high-temperature catalytic oxidation conditions is equivalent to 30 engine hours on an engine lubricant testing device.

Prediction of efficacy and service life of engine lubricants under real use conditions Type of engine gasoline, km traveled Engine oil Predicted in-engine service life Gasoline, limit in thousands kmDiesel, limit in engine hours М-8В7360 *SF/CC15700 SJ/CF Newly developed15750 ВКО Method correlation (1hour of oxidation) with in-engine working period of motor oil Engine oils efficiency prognosisDetermination of engine oil* efficiency in real conditions * API SF/CC Lubricant manufacturer’s recommendation– about 14,000 km traveled

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