The lubricating and cooling capacities of different SAE 20W-50 multigrade engine oil samples were examined in terms of specific heat capacities and cooling rates. Out of the five samples of oil coded as A, B, C, D and E, four of them have very close related values of cooling rates while only B, has a bright-line distinction with a characteristically high cooling rate. Sample E of the multigrade oil samples examined also has the highest specific heat capacity which is suggestive of the high internal energy stored in the lubricating system. The multigrade oil with higher cooling rate is the best coolant and lubricator and the oil sample with highest specific heat capacity has high internal energy that is inversely proportional to viscosity. High energy and less viscous sample (E) lubricates better and starts engines faster than other samples which may have low internal energies and high viscosities when compared with sample E.
