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To evaluate the influence of FAME, which has poor oxidation stability, on engine oil performance, an engine test was conducted under large volumes of fuel dilution by post-injection. The test showed that detergent consumption and polymerization of FAME were accelerated in engine oil, causing a severe deterioration in piston cleanliness and sludge protection performance of engine oil.

Just as CO2 reduction is required of four wheeled vehicles for environmental protection, similar environmental concerns drive the development of motorcycle oil technology. Zinc dialkyldithiophosphate (Zn-DTP) type additives are widely used for engine oil formulations. However, phosphorus compounds are environmental load materials. The reduction of the quantity of phosphorus compounds in engine oils is required to reduce poisoning of three-way catalysts used to purify exhaust gases from internal combustion engines. Mr. Ito and his co-authors1) reported that they developed a sulfur-based additive as a substitute for Zn-DTP. Their non-phosphorus engine oil formulation for four-wheeled vehicles with a sulfur-based additive was examined to evaluate its anti-wear performance using the following test methods:JASO M328 for gasoline engines (KA24E) and JASO M354 for Diesel engine (4D34T4).

At present, the lifetime of engine oil is judged by chemically measuring the changes in its properties while running of an actual vehicle or by setting the standards for its replacement cycle in terms of travel distance and time. The advantage of the former is that the lifetime can be judged with a high degree of reliability, but its disadvantage is that information on the lifetime is difficult for users to obtain. The problem with the latter is that the standards are unreliable. Therefore, users need a simple and reliable method to evaluate the degradation of engine oil so they can determine the appropriate time to change it. We examined the possibility of evaluating the lifetime of engine oil by measuring its capacitance using a comb-shaped electrode. As a result, we found that the capacitance of four types of engine oil collected at markets tended to decrease during the initial stage of degradation and then increased in the later stage.

Engine oils normally contain calcium detergents and ZnDTPs to have detergency and antiwear performance. However, it has been recently understood that these additives could deteriorate filter performance in catalyst and DPF. In this background this paper explains the study and the development about new type of engine oil excluding metal detergents and phosphorus compounds. The developed engine oil shows good durability in several JASO engine tests and a fleet test by formulating newly developed additives as substitute for calcium detergents and ZnDTPs.

In the Japan Clean Air Program II (JCAP II) Diesel WG, effects of fuel properties on the performance of two types of diesel NOx emission aftertreatment devices, a Urea-SCR system and a NOx storage reduction (NSR) catalyst system, were examined. For a Urea-SCR system, the NOx emission reduction performance with and without an oxidation catalyst installed in front of the SCR catalyst at low exhaust gas temperature operation was compared. For an NSR catalyst system, the effect of fuel sulfur on both emissions and fuel economy during 50,000 km driving was examined. Furthermore, effects of other fuel properties such as distillation on exhaust emissions were investigated. The results show that sulfur is the influential factor for both devices. Namely, high NOx emission reduction performance of the Urea-SCR system with the oxidation catalyst at low exhaust gas temperature operation is influenced by sulfur.

High viscosity index(HVI) petroleum base stock, with excellent temperature-viscosity characteristics, oxidation resistance, and low-evaporation properties, offers advantages as the base stock for high fuel economy engine oils, particularly because of its low-friction properties in the boundary and/or “E.H.L (Elastohydrodynamic Lubrication)” area due to its rheological characteristics. This research evaluated HVI base stock's low-friction properties. Upgrading the oil from 5W-30 to 5W-20 was also investigated. The friction properties of the HVI base stock were measured by a unit friction platform. The results show a 28% reduction in friction coefficient compared with the conventional, solvent refined oil, which is attributable to the high-pressure viscosity of the base oil.

Due to increasing demands for further CO2 reduction and tighter exhaust emissions regulations, automakers are increasingly downsizing turbo-charged diesel engines by raising specific power, or adopting low-pressure loop exhaust gas recirculation (LPL-EGR) systems to improve the EGR rate. However, adopting a higher boost pressure to increase the specific power, or introducing hot exhaust gas before the turbocharger compressor with the LPL-EGR system creates higher gas temperatures in the compressor, which results in soot-containing deposits derived from the engine oil in the compressor. This phenomenon causes significant deterioration of turbocharger efficiency. Therefore, countermeasures such as restricting boost pressure or limiting EGR usage in the operational map are necessary to prevent engine performance deterioration. Increasing the gas temperature in the compressor while preventing deposit formation should enable further improvements in fuel consumption and engine power.

Diamond-Like Carbon (DLC) is a promising engine material for reducing friction and wear on sliding parts. By contrast, MoDTC lubricant additives are known to promote the wear of a-C:H films. However, the mechanism that promotes wear and the formation of tribofilms on DLC parts when in contact with molybdenum-based lubricant additives has not been sufficiently studied. The purpose of this research is to determine the wear promotion mechanism and formation of tribofilm on DLC by lubricant additives by comparing friction and wear properties. We conducted friction and wear tests using a tribometer with DLC (ta-C, ta-C:H, a-C, and a-C:H) blocks, FC250 (cast iron) rings, and oils containing lubricant additives (MoDTC, MoDTP, and Mo without DTC ligand) by observing and analyzing the sliding surfaces of specimens. No wear was observed for any of the DLCs (ta-C, ta-C:H, a-C:H, and a-C) in combination with oils containing MoDTP or Mo without DTC ligands.

The deposition of ash derived from engine oil on the surface of diesel particle filters (DPF) has recently been reported to degrade the performance of the DPF. It is generally known that phosphorus in engine oil is adsorbed on the surface of an automotive exhaust catalyst, reducing the performance of the catalyst. Thus, the amounts of ash and phosphorus in engine oil have been decreased. We have developed a non-phosphorus, non-ash engine oil (NPNA) that does not contain metal-based detergents or zinc dialkyldithiophosphate (ZnDTP). Various engine tests were performed, and we confirmed that under normal running conditions, the NPNA oil had a sufficiently high piston detergency and wear resistance-two important requirements for engine oil-to meet current American and Japanese standards. However, the piston detergency of NPNA required further improvement when engine running conditions were more severe.

Recently, deposition of ash derived from engine oil on the surface of a diesel particle filter (DPF) has been reported to worsen the performance of the DPF. It is generally known that phosphorus in engine oil is adsorbed on the surface of an automotive exhaust catalyst and reduces the performance of the catalyst. Thus, the amounts of ash and phosphorus in engine oil have been decreased. We have developed a non-phosphorus and non-ash engine oil (NPNA) that does not contain metal-based detergents and zinc dialkyldithiophosphate (ZnDTP). We performed a performance test for NPNA using an actual engine and reported that the piston detergency and anti-wear performance of NPNA were sufficiently high. However, the piston detergency of NPNA required further improvement when engine running conditions were more severe.

The use of Automatic Transmission Fluids (ATFs) with lower viscosity and excellent anti-shudder durability for wet clutch system will be effective for improving fuel saving performance in automatic transmissions. In this study, two ATF formulation techniques were examined. The first trial formulation is to improve fatigue life in gear components even if a lower viscosity ATF is used. The second one is to improve anti-shudder durability for wet lock-up clutch system in AT units. As to fatigue life performance, the relation between molecular weight of Viscosity Index Improver (VII) and film formation property in EHL contact regions were experimentally investigated. ATFs containing VIIs with lower molecular weight tend to increasing EHL film thickness, resulting in a longer gear pitting fatigue life. Calcium detergents and ashless friction modifiers in ATFs were found to give a great impact on the anti-shudder performance.

As well as a four-wheeled vehicle, in the field of motorcycle, development of the CO2 reduction technology and practical use are required for global environment. Zinc dialkyldithiophosphate (Zn-DTP) type additives are widely used for engine oil formulations. However, phosphorus compounds are environmental load materials. The reduction of the quantity of phosphorus compounds in engine oils is required to reduce poisoning of three-way catalysts used to purify exhaust gases from internal combustion engines. Ito1) reported that they developed a sulfur-based additive as a substitute for Zn-DTP. Their non-phosphorus engine oil formulation for four-wheeled vehicles with a sulfur-based additive was examined to evaluate its anti-wear performance using the following test methods: JASO M328 for gasoline engines (KA24E) and JASO M354 for Diesel engine (4D34T4).