Nano coatings encompass numerous advantages over other conventional coatings, due to unique properties that are small size, control the structure and composition on the nano meter (nm) scale in order to control the properties. The major challenges facing continued growth of nanotechnology based coatings are dispersion, characterization, health and safety and material cost. Recent developments have concentrated on the low heat rejection (LHR) engine applications. This review takes into account the main results achieved up to now, and is focused on the problem facing in LHR engine with nano coating operated on bio-diesel blends.