The dissolved water content in the oil as a function of the oil temperature has a de­ci­sive influence on the lu­bri­cat­ing prop­­er­ties and is therefore an im­por­tant factor in the as­sess­ment of the trouble-free op­er­a­tion of 2/4-stroke en­gines and other ma­chines with ro­tat­ing and linear moving com­ponents.