In-situ high temperature study of the long-term stability and dielectric properties of nanofluids based on TiO2 and SiC dispersions in natural ester oil at various concentrations

•sNF1 sample demonstrates the highest AC BDV during the whole range of ageing.•sNF3 and tNF3 show rapid lack of stability in both temperature conditions.•sNF samples are more stable than tNF samples at the whole range of ageing.•Paper impregnated with sNF1 shows higher resistance to PD by 40% for both cases.•Shallow trapping theory is used to explain the better performance of sNF1.