Hybrid nanofluids has been attracted lots of attention due to simultaneous take advantage of the properties of two or more kinds of nanoparticles in the base fluid. Carbon Nanotubes (CNTs) are utilized widely attached to metal oxide nanoparticles due to significant thermal characteristics. This study aims to assess experimentally the thermal conductivity of the hybrid nanofluid of Zinc Oxide (ZnO) and Multi-Wall CNT (MWCNT) in Engine oil (SAE 10W40). The influences of nanoparticles concentration as well as fluid’s temperature are evaluated. The experiments performed at the temperature between 25 oC and 50 oC and nanoparticles volume fraction from 0.05 to 0.8 %. The experimental results showed that a higher ratio of nano-lubricant thermal conductivity is achieved for a higher volume fraction and temperature of nanoparticles. According to the absence of an exact relationship to determine the thermal conductivity of ZnOMWCNT/ Engine oil, a correlation is developed based on the test measurements presented in terms of volume fraction and temperature using a curve-fitting method. A deviation analysis is also performed on the ratio of thermal conductivity achieved from the developed correlation and experimental data showing a reasonable agreement
