The results of experimental research of cylinder wall wearing process were presented in this article. Researches were conducted onthe basis of four strokes spark ignition one cylinder engine. The main goal of presented research was assessment of impact of cold start condition on intensity of cylinder wall wearing process. The new one and worn engine oil with grade 10W40 was used for experimental research. The experimental research was conducted on specially developed experimental stand. The wear of cylinder wall was assessed on the basis of cylinder diameter and wall roughness measurements.