In the present study, an attempt has been made to understand the impact of the addition of nanoparticles in natural ester oil (nanofluid) on various electro-chemical aspects. In order to stabilize the nanofluid, Cetyl Trimethyl Ammonium Bromide (CTAB) has been used as a surfactant. Various electrical and chemical analysis of nanofluid has been conducted. To analyse the impact of presence of nanoparticles on resistance to electrical stress, corona ageing of oil samples has been carried out. Results indicate higher corona inception voltage (CIV) and lesser window of discharge under phase resolved partial discharge (PRPD) studies in case of stabilized nanofluid. Impact of variation of frequency and addition of harmonics was also analyzed to understand effect of degradation of power supply quality on dielectric properties of oil. It was observed that there is negligible effect of supply voltage frequency for all the samples, whereas a significant decrease was observed in CIV on addition of harmonics. Apart from visual changes, the results acquired from viscosity, turbidity, UV-vis analysis and fluorescence spectroscopy indicates that presence of nanoparticles act as an ageing barrier and helps enhance the lifetime of the insulation. © 2019 IEEE.