The paper proposes a model of tribotechnical diagnostics, which allows us to determine the technical condition of an internal combustion engine within its life cycle and then take measures, including its decommissioning due to excessive wear of major components. The paper also focuses on tribodiagnostic methods that are suitable for assessing the technical condition of internal combustion engines used in various means of transport (automobiles, railway locomotives powered by internal combustion engines, aircraft powered by reciprocating internal combustion engines, special and garden equipment). An internal combustion engine from agricultural equipment was selected for the experiment and monitored throughout its life cycle. The paper describes in detail the appropriate methods used for the proposed tribotechnical diagnostics model, including the results from the measurements by these methods. The said methods were then evaluated and mutually compared. The following advanced instrumental analytical methods were used to evaluate the collected engine oil samples: atomic emission spectrometry (AES), ferrography, automatic laser counter and LNF particle classifier, FTIR infrared spectrometry. The result of the work (paper) is the design of a tribotechnical diagnostics model for determining the technical condition of an internal combustion engine during its life cycle and the determination of limit values for assessing the technical condition of a Honda GCV 165 internal combustion engine. The results are based on individual measurements