It is normal for some of the combustion products of an internal combustion engine to penetrate into the engine lubricant and be retained in it.

When an engine is run for a period of time and then stored over a long period of time, the by-products of combustion may be retained in the oil in a liquefied state.

Under these circumstances, precipitates can form that impair the filterability of the oil the next time the engine is run.

This test method subjects the test oil and the new oil to the same treatments such that the loss of filterability can be determined.

Reference oils, on which the data obtained by this test method is known, are available.

This test method requires that a reference oil also be tested and results reported. Two oils are available, one known to give a low and one known to give a high data value for this test method.

Note 1—When the new oil test results are to be offered as candidate oil test results for a specification, such as Specification D 4485, the specification will state maximum allowable loss of filterability (flow reduction) of the test oil as compared to the new oil.

1.1 This test method covers the determination of the tendency of an oil to form a precipitate that can plug an oil filter. It simulates a problem that may be encountered in a new engine run for a short period of time, followed by a long period of storage with some water in the oil.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.