The oil and gas sector is transforming rapidly, driven by global energy demand and the need to address climate change. Effective maintenance management is critical for ensuring asset reliability and operational safety in this sector, where predictive and proactive strategies replace traditional reactive maintenance practices. This paper introduces a comprehensive maintenance management health framework designed to enhance oil and gas industry maintenance practices. The proposed framework includes six essential stages: asset registration, maintenance strategy selection, capability promotion, maintenance implementation, reporting, and continuous improvement. A key innovation of the framework is using a Health Index (HI), which provides a quantitative and scalable assessment of maintenance management health. This index and its subindices are a benchmarking tool, enabling organizations to compare their performance with industry standards, proactively prevent equipment failures, and minimize downtime. The framework also incorporates modern techniques such as condition monitoring, AI, and digital twins to optimize maintenance efficiency and sustainability. A case study conducted in a gas processing plant with over 10,000 assets demonstrates the practical application of the HI, revealing trends in maintenance health over time and highlighting areas for improvement. The findings underscore the value of the HI in guiding decision-making, improving asset management, and supporting predictive maintenance practices. Furthermore, the study outlines how to integrate predictive methods, optimizing scheduling and planning for maintenance activities, ultimately boosting asset performance and reducing operational disruptions. This framework offers a structured and dynamic approach to maintenance management, promoting continuous improvement and operational excellence in the oil and gas sector