The thermal conductivity measurements of graphene nanoplatelets (GNPs) loaded mineral oil suspensions are obtained using an unconventional custom-made Transient Hot-Wire setup using tungsten. The presence of few layers of graphene in the prepared GNPs using a single step ultrasonication of graphite microparticles without use of a surfactant is verified by AFM, TEM, Raman Spectroscopy, XRD, and XPS techniques. We measured the thermal conductivity and the specific heat capacity (cp) of GNPs loaded mineral oil suspensions. The experimental result shows a maximum of 45.5 % increment in the thermal conductivity of the mineral oil with 1 mg ml-1 (11.481 × 10−4 weight fraction) loading of GNPs at 30 °C. Despite thermal conductivity enhancements, the results indicate that the cp is not compromised, since a low concentration of nanoplatelets were used. The experimental results agree with the Maxwell-Garnett effective medium approach (MGEMA) model for the thermal conductivity of nanofluids which we found to be suitable for lower loading of nanoparticles. We propose GNPs incorporated mineral oil suspensions are effective when it comes to heat transfer fluids even with the lower volume and mass fractions.