This paper investigates the effect of oil contamination on the dielectric performance of Paper-Polypropylene Laminated Paper (PPLP) insulation, which is widely used in high temperature superconducting (HTS) cables. Since PPLP is often exposed to minor contamination from hand oils and sweat during manual fabrication of cable accessories, this study compared the dielectric properties of both pristine and artificially contaminated PPLP samples. The key parameters measured were dielectric loss tangent (tanδ), capacitance, and AC breakdown strength. The experimental results show that oil contamination leads to a reduction in tanδ while simultaneously increasing both capacitance and breakdown strength. The oil-contaminated samples also exhibited greater dispersion and less predictability in their capacitance and breakdown strength compared to the pristine samples. Furthermore, the study found that the failure mechanism of the PPLP did not change due to contamination, as shown by the consistent Weibull shape parameters for both sample types. The findings of this research offer crucial insights for improving manufacturing processes and ensuring the reliability of superconducting cable accessories.