ASTM D8047 Standard Test Method for Evaluation of Engine Oil Aeration Resistance in a Caterpillar C13 Direct-Injected Turbocharged Automotive Diesel Engine
4. Summary of Test Method
4.1 This test method uses a production Caterpillar C13 diesel engine. It is installed on a stand equipped with appropriate instrumentation to record and control various operating quantities. This test is run on an engine that is built with new components and then used for multiple oil evaluations until operational conditions or aeration performance are impacted by the engine condition.
4.2 The test operation involves two test oil flushes of 40 min duration for each test, a test warmup for 40 min and then a test length of 50 h at high-engine-speed (1800 r/min), zero-load conditions.
4.3 The percent aeration of the engine oil is determined using a flow and density meter to continuously monitor the density of a small portion of diverted gallery oil flow that has controlled pressure, temperature, and flow rate. The density of this oil is used to calculate the percentage of total sample volume that is entrained air.
5. Significance and Use
5.1 Background - Prior to this test method, the ability of an engine lubricant to resist aeration was measured by the engine-oil aeration test (EOAT) described in Test Method D6894. The continued availability of engine parts coupled with field service aeration problems led to concerns about the relevance of this test method to newer oil and engine technologies. These concerns prompted the development of this new engine-oil aeration test method, based on the Caterpillar C13 engine and termed COAT. This test method aims to provide a more reliable measurement of the ability of a lubricant to resist aeration during engine operation in field service. The engine used is of current technology and the aeration measurement is operator independent.
5.2 Test Method - This test method evaluates aeration performance under high-engine-speed, zero-load operation in a turbocharged, heavy-duty, four-stroke diesel engine.
5.3 Use:
5.3.1 The tendency of engine oils to aerate in direct-injection, turbocharged diesel engines is influenced by a variety of factors, including engine oil formulation, oil temperature, sump design and capacity, residence time of the oil in the sump, and the design of the pressurized oil systems. In some engine-oil-activated systems, the residence time of the oil in the sump is insufficient to allow dissipation of aeration from the oil. As a consequence, aerated oil can be circulated to hydraulically activated components, adversely affecting the engine timing characteristics and engine operation.
5.3.2 The results from this test method may be compared against specification requirements such as Specification D4485 to ascertain acceptance.
5.3.3 The design of the test engine used in this test method is representative of many, but not all, diesel engines. This factor, along with the unique operating conditions, needs to be considered when comparing the test results against specification requirements.
