ASTM D7320 Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence IIIG, Spark-Ignition Engine
4. Summary of Test Method
4.1 A 3800 series II V-6 test engine block with a displacement of 3.8 L is solvent-cleaned, measured, and rebuilt; using new parts installed as specified in this test method.
4.2 The engine is installed on a test stand equipped with an appropriate data acquisition system, the required fluids process control system, and all necessary accessories for controlling speed, torque, and various other operating parameters.
4.3 The engine is charged with the test oil.
4.4 The engine is operated for an initial run-in period of 10 min to check all test stand operating systems and to establish a zero hour oil level reading and initial oil viscosity sample.
4.5 Following the run-in and oil leveling period of 10 min, the engine is ramped up to test conditions over a 15 min period then operated under non-cyclic, moderately high speed, torque, and temperature conditions for 100 h, in 20 h segments.
4.6 The initial oil level in the oil pan is determined after the 10 min initial run-in, and subsequent oil level calculations are determined during the oil leveling period at the end of each 20 h segment.
4.7 Used oil samples are taken after the 10 min initial run-in and after each 20 h test segment; kinematic viscosity at 40 °C is determined for each of the seven samples; the percentage change in viscosity of the five latter samples is determined relative to the viscosity of the first used oil sample (10 min initial run-in).
4.8 At the conclusion of the test, the engine is disassembled and the parts are visually rated to determine the extent of deposits formed. In addition, wear measurements are obtained.
5. Significance and Use
5.1 This test method was developed to evaluate automotive engine oils for protection against oil thickening and engine wear during moderately high-speed, high-temperature service.
5.2 The increase in oil viscosity obtained in this test indicates the tendency of an oil to thicken because of oxidation. In automotive service, such thickening can cause oil pump starvation and resultant catastrophic engine failures.
5.3 The deposit ratings for an oil indicate the tendency for the formation of deposits throughout the engine, including those that can cause sticking of the piston rings in their grooves. This can be involved in the loss of compression pressures in the engine.
5.4 The camshaft and lifter wear values obtained in this test provide a measure of the anti-wear quality of an oil under conditions of high unit pressure mechanical contact.
5.5 The test method was developed to correlate with oils of known good and poor protection against oil thickening and engine wear. Specially formulated oils that produce less than desirable results with unleaded fuels were also used during the development of this test.
5.6 The Sequence IIIG engine oil test has replaced the Sequence IIIF test and can be used in specifications and classifications of engine lubricating oils, such as the following:
5.6.1 Specification D4485,
5.6.2 Military Specification MIL-PRF-2104, and
5.6.3 SAE Classification J183.
