Two types of N-(4-Octylphenyl)-1-naphthalenamine (OPANA)-based ionic liquids (ILs) were successfully synthesized, demonstrating excellent thermal stability and oil miscibility in pentaerythritol ester oil (PE oil). The ILs can significantly improve the antiwear and antioxidant performance of PE oil. Combined with SEM, EDS, and XPS analyses, the findings indicate that ILs adsorb and react with the worn surface to form a tribo-film, effectively reducing the wear of steel balls. Additionally, ILs are dynamically balanced in PE oil, generating free OPANA to effectively eliminate free radicals produced during high-temperature processes, significantly enhancing the antioxidation performance of PE oil. This study presents a methodology for developing multifunctional additives to improve the use of ILs in industrial lubrication.