Heavy Duty Diesel Engine Oil Research Articles

Correlating wear with the lubricant properties of heavy-duty diesel engine oils

Wear volumes were correlated with the lubricant properties of 11 used, heavy duty engine oil samples. The most important oil property in predicting wear volume is Total Acid Number, TAN. Here, the TAN value may be indicating ZDDP in its oxidised form and unable to participate in corrosive-abrasive wear. Low wear also correlates with mean soot particle size/circularity, which further suggests the abrasive aspect of this mechanism. Finally, low wear correlates with high calcium concentration in the fresh oil. This suggests a new wear reduction mechanism in which calcium from the detergent replenishes the iron within the ZDDP antiwear film.

Oil-lubricated sliding wear performance of TiSiCN-coated ductile iron

Improvements to internal combustion engine performance can be achieved by the application of advanced coatings to piston rings and cylinder bores. Here, the sliding wear performance of TiSiCN coatings on ductile iron was evaluated in heavy-duty diesel engine oil using a block-on-ring tribometer. The coatings were deposited by plasma-enhanced magnetron sputtering of titanium in a reactive environment containing nitrogen, acetylene, and hexamethyldisilazane. Coating characterization was conducted using X-ray spectroscopy and diffraction, electron microscopy, and nanoindentation. TiSiCN adhesion to ductile iron was qualified by Rockwell indentation testing. Wearing surface and counter surface material pairs were systematically varied. Intermittent friction oscillation was observed for self-mated TiSiCN, while tribosystems with only one TiSiCN surface exhibited improved friction stability relative to uncoated ductile iron. A 24% reduction in block wear rate was achieved by coating the block surface with TiSiCN. Solely coating ring surfaces with TiSiCN, however, increased the uncoated block wear rate by over 300%.

Effect of Zinc Dialkyl Dithiophosphate Replenishment on Tribological Performance of Heavy-Duty Diesel Engine Oil

Soot is the main contamination that affects oil performance and increases the frequency of oil changes in heavy-duty engine oil. Several studies discussed that additive concentration in engine oil can be influenced due to additive depletion over time and additive adsorption on soot particles. To extend oil drain intervals and improve oil performance, filter manufactures explore removing the soot to a certain level and replenishing the consumed additives. Zinc dialkyl dithiophosphate (ZDDP) is one of the most favored antiwear additives that react very rapidly with rubbing surfaces to form tribofilm that reduces wear. In this study, the experimental work aims to investigate the effect of ZDDP replenishment on tribological performance in the existence of soot and after removing soot from heavy-duty used oil. The study reveals that reclaiming the used oil can be achieved by removing the soot to a certain level. The results demonstrate that the reclaimed oil after removing soot is still not as good as the fresh oil. This study proves that additive depletion, additive adsorption on soot, and the decomposition of antiwear additive adversely influence the reclaimed oil performance. However, replenishing the consumed additive by adding a small amount of ZDDP helps to improve the reclaimed oil performance compared to a large amount of ZDDP which is required to re-gain the oil performance in the existence of soot.

Factorial study of diesel engine oil contamination effects on steel and ceramic sliding contacts

The present work investigates the effects of diesel contaminants and their interaction on tribological properties for bearing steel (En31) and ceramic (Si3N4) sliding contacts using a factorial study. The contaminants are soot, sulphuric acid, moisture and oxidation, and each contaminant has three different level of concentration (low, medium and high) in the test matrix. The factorial test matrix consisted of 20 tests, constructed from a quarter fractional factorial test matrix with four points at the medium values for the contaminants. Results from this matrix required six further tests to elucidate aliased pairs of interactions using Bayesian model selection. A pin-on-disc tribometer was used to carry out all the experiments. All tests were carried out under ambient conditions at 5 m/s sliding speed and contact stress of 1.5–2.05 GPa to simulate a valve-train in a diesel engine with fully formulated heavy-duty diesel engine oil used as lubricant. Four different tribological properties were studied. The factorial study showed that charge was influenced by tribocouple material; the silicon nitride discs produced higher charge than steel discs. However, it was opposite for friction; the silicon nitride disc gave lower friction and the pins showed higher friction than their steel counterparts. For wear scar and temperature, soot contaminant was found to be important. The two important interactions were found for the charge response, with the interaction between sulphuric acid and pin material being more important than sulphuric acid–oxidation interaction. Similarly to charge, an interaction between sulphuric acid and pin material interaction was found for friction.

The soot handling ability requirements and how to solve soot related viscosity increases of heavy duty diesel engine oil

PurposeThe purpose of this paper is to identify the feature of soot in diesel engine oil and provide a method to stably disperse these soots using effect additives which is benefical for lubricants to pass related engine tests.Design/methodology/approachThis paper designed experiments to investigate the dispersant type, treat level and different dispersant interactions which influence on lubricant soot-related viscosity increase. The research work developed an effective dispersant package which can well solve the soot-related viscosity increase, allowing pass Mack T-11 and Mack T-8 engine tests and demonstrated the helpfulness of using a quickly screening method developed by a steel piston diesel engine CA 6DL2-35.FindingsThe effect of dispersant treat level on the viscosity increase of the oil samples was negligible. Dispersant booster can effectively improve the soot handling ability of heavy-duty diesel engine oils (HDDEO), and the appropriate treat level of dispersant booster can help HDDEO pass Mack T-8 and Mack T-11 engine tests.Practical implicationsThe test results are useful for formulators to select the appropriate dispersants or dispersant booster to develop the HDDEO packages which can meet the modern diesel engine lubrication requirements.Originality/valueMost previous studies in this field were carried out on soot formation mechanism and soot-related wear rather than how to solve the soot-related viscosity increasing of HDDEO. This paper describes the soot dispersing requirements of different HDDEO specifications and developed an effective dispersant package which can well deal with Mack T-11 and Mack T-8E standard engine tests soot handling ability requirements.

The Development of Fuel Economy Test Method for Heavy Duty Diesel Engine Oil (The First HD Engine Test Method and the New JASO DH-2F Category)

The Development of Fuel Economy Test Method for Heavy Duty Diesel Engine Oil (The First HD Engine Test Method and the New JASO DH-2F Category)

The effect of ageing on elastohydrodynamic friction in heavy-duty diesel engine oils

To further improve the efficiency of machine components found in automotive engine systems it is important to understand the friction generation in these components. Modelling and simulation of these components are crucial parts of the development process. Accurate simulation of the friction generated in these machine components is, amongst other things, dependent on realistic lubricant rheology and lubricant properties, where especially the latter may change during ageing of the lubricant. Many modern heavy-duty diesel engines are in operation for several hundred hours before the engine oil is changed. In this work, two engine oils, one 10 W-30 and one 5 W-20, have been aged in full heavy-duty diesel engine bench tests for 400 and 470 hours respectively. This roughly corresponds to the amount of ageing these oils are subjected to between oil drains in field conditions. The aged oils were subjected to a number of oil analyses showing, among other things, a maximum increase in oil viscosity of 12.9% for the 5 W-20 oil and 5.5% for the 10 W-30 oil, which is most likely primarily an effect of evaporation and oxidation. The aged oils were tested in a ball-on-disc test rig under elastohydrodynamic conditions where friction was measured and the performance was compared to fresh samples of the same oils. The results show that there is almost no difference in elastohydrodynamic friction when comparing the aged oils with the fresh oils. These results indicate that it is not necessary to include oil ageing in numerical elastohydrodynamic friction models as long as the oil is changed before the ageing has reached a critical level.