The characteristics of some Nigerian engine oil, petrol and fuel mixture were studied. Engine oil, petrol and fuel mixture are used daily on the Nigerian roads, homes, offices etc. in various machines (engines) as lubricating oils. One important use of these lubricating oils is to reduce friction between parts of a machine in relative motion. The measurement of viscosity of the engine oil and fuel mixture was carried out to determine the characteristics of the oil and the blend with respect to their use. Using an Ostwald Viscometer method, the viscosities of the engine oil and petrol were found to be 1.192 centiPoise (cP) and 0.751 centiPoise (cP) respectively. Various blend mixtures of the petrol and engine oil also gave good results. The results indicate that the viscosity increases with increase in the proportion of engine oil. The time of flow and density also increases as the volume of engine oil increases. The changes in densities and viscosities of the blend were found to be drastic while the proportion of the petrol in the blend increases. The changes were found to be gradual while the proportion of petrol in the blend was less.