ASTM D5302 Standard Test Method for Evaluation of Automotive Engine Oils for Inhibition of Deposit Formation and Wear in a Spark-Ignition Internal Combustion Engine Fueled with Gasoline and Operated Under Low-Temperature, Light-Duty Conditions
4. Summary of Test Method
4.1 Each test engine is assembled with many new parts and essentially all aspects of assembly are specified in detail.

4.2 The 2.3-L internal combustion engine is installed on a test stand, which is equipped to control speed and load and various other operating parameters.

4.3 The engine is operated for a total of 288 h, consisting of 72 repetitive cycles of 4 h each. Each cycle consists of three stages.

4.4 While the operating conditions are varied within each cycle, overall they can be characterized as a mixture of low-temperature and moderate-temperature, light-duty operating conditions.

4.5 To accelerate deposit formation and engine wear, the level of oxides of nitrogen in the blowby and the rate of blowby into the crankcase are significantly increased, the fresh air breathing of the crankcase is significantly decreased, and the transitions between two of the stages of operation are deliberately enriched, in comparison with normal operation.

4.6 The test engine oil's performance is determined at the end of the test by dismantling the engine and measuring the deposition and wear.

5. Significance and Use
5.1 This test method is used to evaluate an automotive engine oil's control of engine deposits and wear under operating conditions deliberately selected to accelerate deposit formation and wear. This test method was correlated with field service data, determined from side-by-side comparisons of two or more oils in taxi fleets and delivery van services, as examples. The same field service oils were then used in developing the operating conditions of this test procedure.

5.2 This test method, along with other test procedures, defines the minimum performance level of the API Categories SH and SJ (detailed information about these categories is included in Specification D4485). This test method is also incorporated in U.S. Army and automobile manufacturers' factory-fill specifications.

5.3 The basic engine used in this test method is representative of many that are in modern automobiles, but not all. This factor, along with the accelerated operating conditions, should be considered when extrapolating test results.