5.1 Coagulated pentane insolubles can include oil-insoluble materials, some oil-insoluble resinous matter originating from oil or additive degradation, soot from incomplete diesel fuel combustion, or a combination of all three.

5.2 A significant change in coagulated pentane insolubles indicates a change in oil, and this could lead to lubrication system problems.

5.3 Coagulated pentane insolubles measurements can also assist in evaluating the performance characteristics of a used oil or in determining the cause of equipment failure.

5.4 High values of coagulated pentane insolubles have been associated with plugged oil filters, leading to opening of the bypass valve and circulation of unfiltered oil in the engine. This can lead to increased piston deposits, increased bearing wear, and premature engine failure.

1.1 This test method covers the determination of coagulated pentane insolubles in used lubricating oils by a paper filtration method.

1.2 This test method was originally developed by the Fuels, Lubricants, and Environmental Committee (FL&E) of the Locomotive Maintenance Officer’s Association (LMOA).²

1.3 This test method is used primary for testing used diesel engine oils from railroad locomotive service. It may be applied to other samples types but precision, bias, and significance have not been determined for samples other than used railroad locomotive diesel engine oils.

1.4 This test method, in general, does not correlate with Test Method D893 on Insolubles in Lubricating Oils, since it uses separation by centrifugation and a more concentrated solution of anti-coagulant.

1.5 The correlation between this test method and Appendix A4 (Enhanced Thermal Gravimetric Analysis (TGA) Procedure) in Test Method D5967 has not been investigated.

1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 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 7.2, 7.3, and 7.4.