ASTM D6618 Standard Test Method for Evaluation of Engine Oils in Diesel Four-Stroke Cycle Supercharged 1M-PC Single Cylinder Oil Test Engine
4. Summary of Test Method
4.1 Prior to each test run, the power section of the engine (excluding piston assembly) is completely disassembled, solvent-cleaned, measured, and rebuilt in strict accordance with furnished specifications. A new piston, piston ring assembly, and cylinder liner are installed each test. The engine crankcase is solvent-cleaned, and worn or defective parts are replaced. The test stand is equipped with appropriate accessories for controlling speed, fuel rate, and various engine operating conditions. A suitable system for supercharging the engine with humidified and heated air shall also be provided.
4.2 Test operation involves the control of the supercharged, single-cylinder diesel test engine for a total of 120 h at a fixed speed and fuel rate, using the test oil as a lubricant. A 1 h engine break-in precedes each test. At the conclusion of the test, the piston, rings, and cylinder liner are examined. Note the degree of cylinder liner and piston ring wear, the amount and nature of piston deposits present, and whether any rings are stuck.
5. Significance and Use
5.1 The test method is designed to relate to high-speed, supercharged diesel engine operation and, in particular, to the deposit control characteristics and antiwear properties of diesel crankcase lubricating oils.
5.2 The test method is useful for the evaluation of diesel engine oil quality and crankcase oil specification acceptance. This test method, along with others, defines the minimum performance level of the API categories CF and CF-2 (detailed information about passing limits for these categories is included in Specification D4485). It is also used in MIL-PRF-2104.
5.3 The results are significant only when all details of the procedure are followed. The basic engine used in this test method has a precombustion chamber (as compared to direct injection) and is most useful in predicting performance of engines similarly equipped. This factor should be considered when extrapolating test results. It has been found useful in predicting results with high sulfur fuels (that is, greater than 0.5 wt %) and with certain preemission controlled engines. It has also been found useful when correlated with deposit control in two-stroke cycle diesel engines.
