Mathematical analysis of soot particles in oil used as system state indicator

Different state indicators are used when assessing technical systems. If we are to use indirect diagnostic measures, lubrication oil seems to be a good source of different information. It is possible to get the information on the state of the oil and the system. In our article we focus on specific oil particles, i.e. soot. It is formed as a by-product during fuel combustion. Soot contaminates the oil and its concentration might indicate that operation conditions are getting worse. The essential and interesting thing is that some additives in the oil are able to dissolve the soot. In our article we introduce some results obtained from processing oil soot data. The data introduced depend on a few operating measures - kilometres [km], days [day] and moto-hours [Mh]. In the analysis we use deterministic and fuzzy mathematical methods. Our aim is to estimate and study the hitting time of a critical threshold.