What are Pentane Insolubles, Toluene Insolubles, Benzene insolubles, and Heptane Insolubles? And its role in Lube oil testing.

Lubricating oils are essential components in modern machines and engines, as they ensure smooth operation and protect against wear and tear. However, over time, these oils can degrade, leading to reduced performance and potential damage to the equipment. That’s where lubricant testing comes in, which involves analyzing various properties of the oil to determine its quality and condition. One such test is the determination of insoluble matter in oils, which can be divided into different categories depending on the solvent used. 

Insolubles can be defined as solid material that does not dissolve in the oil but instead forms solid particles or sludge which can be separated from the oil centrifugation or filtration when a solvent (either pentane, toluene, benzene or heptanes) is added. 

Regular use of lube oils causes them to gradually gather trace amounts of foreign substances and dust particles that stay suspended in the oil, increasing viscosity, decreasing fluidity, and decreasing filterability, which can ultimately result in equipment failure. In engines and systems which run on combustion, particles such as dust, dust, silicates, wear metals, organic oxides, soot mix themselves in the oil. The condition of the oil will be determined by the total amount of all these insolubles.

• Pentane insolubles are the organic oxides and resinous bitumen produced from oxidation of the fuel or oil formed due to additive degradation
• Toluene insoluble are the soot, dust particles, silica, silicates and wear metals in the oil
• Benzene insolubles consists of all pentane insolubles except resinous oxidation products
• Heptane insolubles are mainly the asphaltenes produced in the lubricating oil or fuel Atlas Lab uses the following methods for testing of insolubles which are listed as under :