Search Results

The SAE Engine Oil Viscosity Classification (EOVC) Task Force has been gathering data in consideration of extending SAE J300 to include engine oils with high temperature, high shear rate (HTHS) viscosity below the current minimum of 2.6 mPa⋅s for the SAE 20 grade. The driving force for doing so is fuel economy, although it is widely recognized that hardware durability can suffer if HTHS viscosity is too low. Several Japanese OEMs have expressed interest in revising SAE J300 to allow official designation of an engine oil viscosity category with HTHS viscosity below 2.6 mPa⋅s to enable the development of ultra-low-friction engines in the future. This paper summarizes the work of the SAE EOVC Low Viscosity Grade Working Group comprising members from OEMs, oil companies, additive companies and instrument manufacturers to explore adoption of one or more new viscosity grades.

The laboratory tests used to define API GL5 have been the cornerstone of gear oil development for well over thirty years. In that time they have served the market very well. Lubricants developed with these test methods have provided adequate protection of axle components from severe wear, scuffing, corrosion, and oxidation. Recently, however, there has been an increasing trend toward extended drain intervals which changes the picture. Coupled with longer oil drain intervals there is a continuing increase of power throughput in the equipment. The combination of increased power and extended service life places significant stress on the oil such that the load carrying ability and thermal and oxidative stability could be greatly diminished under these conditions. During the past ten years the industry has been actively working toward a new gear oil specification that will address the performance needs of today's vehicles.

The ASTM D6121 (L-37) is a key hypoid gear lubricant durability test for ASTM D7450-08 (API Category GL-5) and the higher performance level SAE J2360. It is defined as the ‘Standard Test Method for Evaluation of Load-Carrying Capacity of Lubricants Under Conditions of Low Speed and High Torque Used for Final Hypoid Drive Axles’. Pass/fail is determined upon completion of the test by rating the pinion and ring gears for several types of surface distress, including wear, rippling, ridging, pitting, spalling and scoring. Passing the L-37 in addition to the other tests required for API Category GL-5 credentials, as well as the more strenuous SAE J2360 certification, requires in-depth formulating knowledge to appropriately balance the additive chemistry. This paper describes the results of ASTM D6121 experiments run for the purposes of better understanding gear oil durability.

Automatic transmission clutches are complex tribological systems. Frictional performance is controlled by the interaction of base fluids, additive components, composition clutches, and steel reaction plates with varying energy inputs and thermal stresses in an oxidizing environment. This paper, rather than addressing fully formulated fluid performance in such a system, takes a more fundamental approach where the number of system variables is reduced and the relative effects of formulation variables on system performance can be better examined. Relationships among observed friction performance, system oxidation, friction member condition, and representative performance additives are explored using a synthetic base fluid and a conventionally refined mineral base fluid.

The Cooperative Lubrication Research (CLR) Oil Test Engine, usually called the L-38, has been used for nearly 25 years to evaluate copper-lead journal bearing protection of gasoline rnotoroils under high-temperature, heavy-duty conditions. The test is sensitive to aggressive surface active additives that may encourage bearing corrosion. The L-38 also provides an estimate of oil durability, assessing the resistance of an oil to the accumulation of acidic by-products of combustion that could attack copper-lead bearings. However, the L-38 engine dynamometer test uses a heavily leaded gasoline that is no longer representative of the commercial fuels available in North America, Europe, or Japan. Rather than discard the L-38, this paper describes work to modify the L-38 procedure to run with unleaded gasoline.

Nylon is used as a material in the design of various components of automatic transmissions. Pump rotor guides and thrust washers are among components designed from nylon. Nylon must be compatible with automatic transmission fluid (ATF). An immersion test using nylon strips in various test fluids was developed. The nylon color change was independent of the physical properties (as measured by change of tensile force) of the material. Testing indicated that nylon color change is catalyzed by oxidation effects, and the change in tensile strength is related to thermal degradation. An automatic transmission fluid (ATF) containing calcium sulfonate detergent showed better oxidation resistance and caused less loss of tensile strength in nylon 6 (PA6).

THIS paper presents the results of a controlled field test of heavy-duty crankcase oils in a fleet of 15 Chevrolet cars. Operating conditions were selected to represent average or typical passenger-car service. After 15 months of operation (approximately 14,000 miles on each car) it was found that, in comparison with the results obtained with a nonadditive oil, a heavy-duty oil of MIL-0-2104 performance level reduced piston-ring wear by 37%, reduced cylinder-bore wear by 42%, and significantly improved engine cleanliness.

A study was made of passenger car engine oil drain intervals from 1946 to the present time. The drain intervals were intercompared with engine tests used to gauge oil performance and trends in automotive emission control. Preliminary data from vehicle tests show that the technology may be available to achieve longer drain intervals in today's automobiles. With the stipulation that the extended drain capabilities of an oil formulation must be qualified in relation to the type of service and the type of gasoline used (i.e., leaded or unleaded fuel), taxicab data show that higher quality levels then current API SE are needed to double today's recommended oil change intervals. Engine wear appears to be the major technical limitation on extending oil change intervals. Other technical limitations are control of engine deposits and resistance to oil thickening.

Diesel engine oils containing a balanced additive package composed of oxidation, corrosion, wear, rust and foam inhibitors plus ashless dispersants and metallic detergents provide long engine life. The major factor is metallic detergent component which contributes alkalinity to the oil and has a direct effect on engine cleanliness and durability. Increased detergent alkalinity reduces deposits and wear, resulting in improved oil control and longer engine life. Careful selection of detergent components is required to control cylinder-bore polishing in diesel engines to assure optimum antiwear and oil control performance.

The specific goal of this project was to determine if there is a difference in the lube oil degradation rates in a heavy-duty diesel engine equipped with an EGR system, as compared to the same configuration of the engine, but minus the EGR system. A secondary goal was to develop FTIR analysis of used lube oil as a sensitive technique for rapid evaluation of the degradation properties of lubricants. The test engine selected for this work was a Caterpillar 3176 engine. Two engine configurations were used, a standard 1994 design and a 1994 configuration with EGR designed to meet the 2004 emissions standards. The most significant changes in the lubricant occurred during the first 50-100 hours of operation. The results clearly demonstrated that the use of EGR has a significant impact on the degradation of the engine lubricant.

It has long been understood that the piston assembly of the internal combustion engine accounts for a significant proportion of total engine friction. Modern engines are required to have better fuel economy without sacrificing durability. The pursuit of better fuel economy drives trends like downsizing, turbocharging and direct injection fuelling systems that increase cylinder pressures and create a more arduous operating environment for the piston ring / cylinder bore tribocouple. The power-cylinder lubricant is therefore put under increased stress as modern engine technology continues to evolve. The conventional approach to investigating fundamental power-cylinder tribology employs bench-tests founded on assumptions which allow for simplification of experimental conditions.