Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.1 Key Condition Indicators for Lube Oils >> 7.1.4 Insolubles
Insolubles testing of diesel engine oils
This test is really only applicable to diesel engine oils where the typical contamination levels far exceed those of any other lubricant system. The single exception is some aviation derived gas turbines that are prone to a problem known as ‘Black Oil’.
Laboratory measurement of Insolubles by ASTM D893 is the industry-accepted reference method. Measurements of insolubles may also include Total Insolubles by IP316 using heptane as the solvent and has relatively good correlation to ASTM D893. Other proprietary tests exist (e.g. IC Photometer) mainly providing an indication of carbon content, wear metal and metallic fuel ash and airborne grit.
The dispersancy and detergency of the lubricator oil will be affected and this will quicken the tendency for deposit build-up around the upper piston and piston ring pack. Insolubles levels will generally rise with engine wear. This can then fall again as oil consumption becomes the dominant factor in a very worn diesel engine.
High insoluble levels will cause:
Insolubles in engine oil consist of:
