Two types of greases, namely, lithium- and caoutchouc-thickened greases, used to lubricate the moving parts of huge heavy machines operating in outdoor environments are selected and their thermal properties are investigated using both experimental and numerical methods. A test setup for simulating the actual operating conditions is prepared. The temperature and torque variations of greases without additives and with microparticle additives are analyzed in the test setup. ZnO (zinc oxide), a semiconductor material that relies on high energy electromagnetic radiation as an additive, is tested by mixing it into greases in weight fractions. The radiative properties are analyzed in the visible and the infrared wavelength ranges of 2.5‒20 μm. Furthermore, the experimental results are validated by the discrete dipole approximation (DDA) method by evaluating the absorption efficiency factors. The obtained results are presented with the changes in momentum, temperature and absorption values. The temperature and torque distributions vary according to the weight fractions of the metallic microparticles and the type of greases. The caoutchouc-thickened grease reaches higher torques than the lithium-thickened grease. The absorption values of the greases with additives are smaller than the greases without additives in the near-infrared wavelength. Therefore, it is seen that greases with additives can quickly eliminate the heat generated in the moving parts of heavy machines.