Modern Engine Oils Research Articles

New method of assessment of technical condition of vehicle internal combustion engines in the course of their long-term operationх длительной эксплуатации

Introduction (problem statement and relevance). Modern control over the vehicle engine technical condition is performed by measuring the coolant temperature and oil temperature.The purpose of the study is to examine the regularities of engine oil aging with determination of the causes of change of oil performance indicators, assessment of its admissible state and identification of optimal timing for its replacement according to the actual condition.Methodology and research methods. The results of bench and operational tests of three modern engine oils at long-term run in the KAMAZ family engines were analysed. Scientific novelty and results. The article presents the justification of usage of blow-by, which characterizes the rate of wear of the main friction surfaces inside the cylinder-piston and valve train group of parts, as an objective indicator of the engine technical condition.Practical significance. For further research, the problematic issues regarding technical condition quality control and service life increase for the vehicle internal combustion engine have been outlined.

Abstracts

New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphate dash, phosphorus and sulfur. This thesis describes the impact of adding lubricant additives on the visco-elastic and thermo-physical properties of engine oils. The engine oils used in automotive industry are one of the most widely used consumable entities. There has been an ever increasing demand to improve the performance of engine oil lubricants. For that purpose, performance enhancing additives have been added to engine oil lubricants since past few decades. Subsequently, there is an ever increasing need to show the contribution lubricant additives make towards the automotive industry, the consumer and the impact on the environment. Such additives encompass applications for lubrication of passenger car (diesel and gasoline engine) lubricants, truck, coach and bus diesel engine lubricants, heavy duty engine oil etc. The document demonstrates the contribution made by lubricant additives in these applications to the consumer, industry and the environment, through their ability to optimise desirable lubricant properties while suppressing unwanted ones.

The science and technology of using nano-materials in engine oil as a lubricant additives

New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphate dash, phosphorus and sulfur. This thesis describes the impact of adding lubricant additives on the visco-elastic and thermo-physical properties of engine oils. The engine oils used in automotive industry are one of the most widely used consumable entities. There has been an ever increasing demand to improve the performance of engine oil lubricants. For that purpose, performance enhancing additives have been added to engine oil lubricants since past few decades. Subsequently, there is an ever increasing need to show the contribution lubricant additives make towards the automotive industry, the consumer and the impact on the environment. Such additives encompass applications for lubrication of passenger car (diesel and gasoline engine) lubricants, truck, coach and bus diesel engine lubricants, heavy duty engine oil etc. The document demonstrates the contribution made by lubricant additives in these applications to the consumer, industry and the environment, through their ability to optimise desirable lubricant properties while suppressing unwanted ones.

The challenges and benefits of using carbon nano-tubes as friction modifier lubricant additives

The engine oils used in automotive industry are one of the most widely used consumable entities. There has been an ever increasing demand to improve the performance of engine oil lubricants. For that purpose, performance enhancing additives have been added to engine oil lubricants since past few decades. Subsequently, there is an ever increasing need to show the contribution lubricant additives make towards the automotive industry, the consumer and the impact on the environment. Such additives encompass applications for lubrication of passenger car (diesel and gasoline engine) lubricants, truck, coach and bus diesel engine lubricants, heavy duty engine oil etc. The document demonstrates the contribution made by lubricant additives in these applications to the consumer, industry and the environment, through their ability to optimise desirable lubricant properties while suppressing unwanted ones. New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphated ash, phosphorus and sulfur. This thesis describes the impact of adding lubricant additives on the visco-elastic and thermo-physical properties of engine oils. In this paper the benefits and challenges of Carbon Nanotubes as Lubricant additives has been discussed in detail.

The characterization analysis of multi walled carbon nanotubes coated with carboxylic group compounds to improve its dispersion properties in mineral base engine oils

This paper describes the impact of adding lubricant additives on the viscoelastic and thermo-physical properties of engine oils. From the literature survey it was deduced that there was a need to fully understand how nano-tubes based lube oil solutions will behave mechanically and thermally and one needs devoted work for better and detailed experimentation. New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphated ash, phosphorus and sulfur. It is quite obvious from the detailed research papers analysis that the researchers are still pretty far from achieving full potential these nanotubes have. The environment is taking toll because of the use of harmful lubricants and the issue needs to be addressed through proper studies. The compatibility of nano particles with lubricants synergistic effect with many forms of lubricant oils needed to be further investigated. The structural characteristics needed to be explored and understood in more details with firmly evidence with the help of modern analytic methods, such as Scanning Electron Microscopy and Field Emission Scanning Electron Microscopy.

The Role of NOx in Engine Lubricant Oxidation

<div class="section abstract"><div class="htmlview paragraph">Fuel economy trends like engine downsizing and reduced piston ring tension have created challenging environments for modern engine oils which are expected to deliver more from less. Downsizing has led to smaller sumps meaning longer contact times of the lubricant with NOx in blow-by gasses. Fuel economy requirements have also demanded greater engine efficiency with increasing sump temperatures and blow-by rates due to reduced ring tension. These trends promote nitro-oxidation driven by the action of NOx and air on the lubricant. Nitro-oxidation has often been overlooked as a mechanism of oil oxidation in real world engines. Indeed, in bench oxidation tests purporting to protect modern engines against lubricant oxidation, the emphasis is almost exclusively on iron catalysed oxidation. This paper will show that a simple bench nitro-oxidation test is capable of reproducing trends in nitrate ester formation and consumption seen in real engines and demonstrate that lubricant oxidation and viscosity increase is accounted for by the action of NOx without the use of iron catalysts. This demonstrates that the initiation of lube oil oxidation in real engines is due to the action of NOx and it is only later in the oil life cycle that iron plays any significant role. This has important implications for the widespread use of iron-catalysed bench oxidation tests as guardians for oxidation performance in the real world. Because the oxidation observed in iron catalysed bench oxidation tests does not include NOx, the initiation and propagation of oxidation proceeds via a different mechanism and requires a different anti-oxidant solution.</div></div>

The concept of evaluation of reliability of modern engine oils in operation

The article presents the concept of modern engine oils reliability assessment. The strategy taken in practice for changing the engine oil based on a predetermined working time may lead to the replacement of engine oil being still in operational condition caused by the selected status parameter. Such conclusions are coming from the conducted tests of mineral oils. It is reasonable to carry out reliability of engine oils assessment in operation, for synthetic oils dominating on the automotive market.

Performance of Friction Modifiers on ZDDP-Generated Surfaces

Most modern engine oils contain a friction modifier additive to reduce boundary friction and thus contribute to improved fuel economy. Considerable research work has been carried out to measure the effectiveness of friction modifiers, both in base oil and in fully formulated engine oils. Most of this work has studied the behavior of friction modifiers on rubbing ferrous surfaces. However, engine oils generally also contain the antiwear additive zinc dialkyldithiophosphate (ZDDP) and it is well known that this additive reacts rapidly with rubbed ferrous surfaces to form a thick iron and zinc phosphate-based coating. Thus, to be effective, a friction modifier additive has to form a friction-reducing film not on a ferrous surface but on a zinc phosphate one. In the current study, the friction-reducing properties of friction modifiers on steel surfaces have been compared with their performance on surfaces having a ZDDP reaction film coating. It has been found that additives that are effective in reducing friction on steel surfaces are not necessarily effective in reducing friction on a phosphate coating and vice versa. The reasons for these observed differences are discussed.

Characterization of anti-wear films formed from fresh and aged engine oils

Modern engine oils are formulated with zinc dialkyl-dithiophosphate (ZDDP) compounds to protect moving metal components from wear. As emissions regulations for automobiles become more stringent, lower concentrations of these additives are being considered in future oil formulations to extend the life of the catalyst after-treatment systems. However, any formulation changes need to be carefully tested to ensure there is no degradation in friction and wear performance. While evaluating engine oils in a prior study, we found that the valve-train wear improved markedly as the oil aged. Changes in tribological performance were linked to differences in surface film chemistry on the valve tappet components. In the current study, we examine the friction and wear of fresh and aged engine oils in controlled laboratory tests using a simulated valve-train apparatus, ball-on-flat, and cylinder-on-flat test rigs. Surface films that form during sliding were characterized at different length scales and depth distributions using reflection infrared spectroscopy, Raman spectroscopy, and high-vacuum surface analysis. The types of species present, such as phosphates, were different between fresh and aged oil. Carbonate and sulfide were present in films formed from fresh oil, but were usually absent from aged oil. Wear control may be related to a competition between carbonate and phosphate species. Oxidized-oil-derived entities are present on aged oil coupons and appear to improve friction performance. Thus, differences in film composition are used to explain performance differences of fresh and aged oils and the results from the different test rigs.

Preparation and Evaluation of Some Lube Oil Additives Based on Polyethylene Glycol

Among the various additives employed in modern engine oils, one of the most important is the type that acts to prevent an accumulation of sludge in the crankcase and on the cylinder walls, thereby preventing sticking of piston rings and the formation of varnish-like coatings on the pistons and cylinder walls. Because of their general function of maintaining a clean engine, additives of this nature are termed detergents although it is now understood that they have little utility in cleaning a dirty engine, but by virtue of dispersing activity, prevent engine fouling. A main source of deposits is the oxidation of oil in high temperature, which can be reduced by using antioxidants. This work was limited to the preparation and characterization of different types of polyethylene glycol palmitate with different molecular weights and amination of the prepared esters with tetraethylenepentamine. The efficiency of the prepared compounds as detergents/dispersants and antioxidants was investigated and the effect of the prepared additives on other properties of lube oil was also studied. It was found that all the prepared compounds act as detergents/dispersants and antioxidant additives with no effect on the viscosity index and pour point of the lube oil.

Chemical and Physical Analysis of Reaction Films Formed by Molybdenum Dialkyl-Dithiocarbamate Friction Modifier Additive Using Raman and Atomic Force Microscopy

In order to improve the fuel economy of engines it is now common to include in modern engine oils small quantities of soluble, molybdenum-based friction-reducing additives. These additives are generally believed to form MoS2 in rubbed contacts and thereby reduce friction in boundary lubrication conditions. This paper describes the application of Raman and atomic force microscopy to study the reaction films formed in rubbing contacts by simple solutions of molybdenum dialkyl-dithiocarbamate additive. Raman microanalysis shows that MoS2 is present in the wear scars produced whenever this molybdenum additive effectively reduces friction. In reciprocating friction tests, the MoS2 is unevenly distributed in the wear scar, with more in the centre of the stroke than at the reversal points. This explains the experimentally observed influence of stroke length on friction. Atomic and lateral force microscopy show that when the additive effectively reduces friction, tiny, discrete, flake-like low friction domains are present in the wear scar. These are typically 10–25 nm in diameter and 1–2 nm thick and are believed to represent MoS2 nanocrystals as have been previously reported in the literature using high-resolution TEM. Coupled topography and lateral force measurements shows that these nanocrystals are present only on the high spots of the rubbed surface.

The Relative Wear Performance of Neutral and Basic Zinc Dithiophosphates in Engines©

Over the years, many bench tests have been used to guide synthetic organic chemists in their quest for new molecules to prevent valve train wear. Which bench tests to choose has always been an important issue, especially when the goal is to prevent valve train wear in an internal combustion engine, a very complicated system. Essential antiwear additives in modern engine oils are zinc dithiophosphates (ZnDTPs) and, although these materials have been used extensively, the fundamental mechanisms of their chemistries are not that well understood. In this paper, several nontraditional bench tests have been evaluated, some involving surfaces but no rubbing, and others lacking rubbing surfaces entirely. Despite these apparent deficiencies, these nontraditional chemistry-based tests all could be interpreted to predict a wear advantage for the neutral ZnDTP species relative to the basic ZnDTP species. This paper reports on engine tests of a neutral commercial-like ZnDTP and a basic commercial-like ZnDTP, with the result supporting the interpretation of the nontraditional bench tests: the neutral ZnDTP is better than the basic ZnDTP in engines with respect to valve train wear performance, with high statistical significance. Fundamental understanding of the chemistry of neutral and basic ZdTP has been shown to yield a practical result. Presented at the 53rd Annual Meeting in Detroit, Michigan May 17–21, 1998

Synthesis and Tribofragmentation of Monothio-Phosphates

Abstract Besides the well-known zinc dithiophosphates (ZDTP) phosphorus and sulfur containing ashless additives are used to improve the lubrication properties of modern engine and hydraulic oils. It is generally accepted that a wear reducing reaction layer is formed by additive tribofragmen-tation reactions in the friction zone of the metal surface. The composition of those reaction layers and the formation mechanism relative to the used additive is quite unknown. By systematic modification of monothiophosphates the influence of molecule parameters on the wear reducing properties were investigated (1).