Pentane insolubles can include oil-insoluble materials and some oil-insoluble resinous matter originating from oil or additive degradation, or both.

Toluene insoluble materials can come from (1) external contamination, (2) fuel carbon and highly carbonized materials from degradation of fuel, oil, and additives, or (3) engine wear and corrosion materials.

A significant change in pentane insolubles, toluene insolubles (with or without coagulant), and insoluble resins indicates a change in oil which could lead to lubrication system problems.

Insolubles measured can also assist in evaluating the performance characteristics of a used oil or in determining the cause of equipment failure.

1.1 This test method covers the determination of pentane and toluene insolubles in used lubricating oils.

1.2 Procedure A covers the determination of insolubles without the use of coagulant in the pentane. It provides an indication of the materials that can readily be separated from the oil-solvent mixtures by centrifuging.

1.3 Procedure B covers the determination of insolubles in oils containing detergents and employs a coagulant for both the pentane and toluene insolubles. In addition to the materials separated by using Procedure A, this coagulation procedure separates some finely divided materials that may be suspended in the oil.

Results obtained by Procedures A and B should not be compared since they usually give different values. The same procedure should be employed when comparing values obtained periodically on an oil in use or when comparing results determined by two or more laboratories.

1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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. For specific warning statements, see Section and .