What is commonly used nanofluid coolant for automobile radiator ? And any specific reason for that coolant ?
Nanofluid coolant is basically part ethylene-glycol heat transfer agent from regular coolant and part water with suspended sub 100 nanometer-sized particles (CuO, for example) which boasts better heat conductivity than regular coolant.
I'm not sure this is the one you are talking about, as I've never seen it used in cars in practice, only read about them in scientific papers where they are tested as potential replacement for conventional coolant. It is sometimes used in computer water cooling systems by computer building enthusiasts, though.