Nanofluid or suspension of nanoparticles in a base fluid, is name of a new kind of engineering material that is believed to have higher thermal conductivity comparing to that of the base fluid. Base fluids such as water, ethylene glycol or anti freezant and different types of oils have low thermal conductivity. These fluids can be found in industrial applications as heat conveyers. Wide range of nanoparticles such as metallic, oxide metallic and nonmetallic like carbon nano tubes (CNT) have been used to prepare nanofluids and their thermal conductivity have been reported to be higher than the base fluid, but the reported numbers are different. In the present investigation, thermal conductivity and heat capacity of suspensions of alumina and copper oxide nanoparticles in engine oil were measured for different temperatures, ranging from 20 to 80 degrees centigrade and for different nanoparticle concentration, up to 2 volume percent. The effects of temperature and concentration of nanoparticles on thermal conductivity and heat capacity have been investigated. Comparing to other attempts, this project have two new aspects, first, the engine oil that has been used as base fluid and second, measuring heat capacity of prepared nanofluids. There are some reports about measuring thermal conductivity of engine oil based carbon nanotube suspensions, but there is no report about using metallic oxide nanoparticles. Heat capacity is also another important thermal property that has not been under consideration of researchers. Thermal conductivity was measured by hot wire transient method. The basis of this method is on the radial distribution of heat in an infinite media. Thus thermal conductivity is determined by measuring temperature in the center of wire, in various time intervals during an unsteady process. Name of the used device was KD2, a product of Decagon Device Inc. . By adding 2 volume percent alumina nanoparticles, thermal conductivity of engine oil increased about 5 percent. Adding copper oxide nanoparticles to engine oil by 2 volume percent, it’s thermal conductivity enhanced about 9 percent. A linear relationship was seen between thermal conductivity enhancement of nanofluids and the volume percent of used nanoparticles. Thermal conductivity of nanofluids decreased with increasing temperature and the behavior was like that occurred for pure engine oil. Also enhancement of thermal conductivity was lower in upper temperatures. Uncertainty of measurements ....