Abstract
Lubricating oil is used in various machines and devices. However, lubricating oil is degraded with operating time or usage environment. Degradation causes of the lubrication oil are roughly classified into two types, one is caused by solid particle and other is caused by oil oxidation products. Diagnosis methods for solid particles in lubricating oils have many standards and researches. However, there are few diagnosis methods for oil oxidation products. In this study, we investigated to establish the relationship between the color of contaminants trapped on a filter after filtering degraded oil and properties of the lubricating oil, and developed diagnosis method of the lubricating oils using the colorimetric analysis which paid to the attention to the color of contaminants. These results suggested the feasibility of new diagnosis method of the lubricating oils by the colorimetric analysis.
