Advanced manufacturing in Saudi Arabia is moving from capacity expansion toward digitally enabled productivity, reliability, localization, and resource efficiency. This review examines how four complementary mechanisms—predictive maintenance, Overall Equipment Effectiveness (OEE), digital twins, and Lean Six Sigma—can be integrated to optimize advanced manufacturing machinery under the industrial priorities of Saudi Vision 2030. A structured integrative review of literature published from 2020 to 2025 was undertaken across smart manufacturing, maintenance engineering, production performance, digital-twin applications, and operational excellence, with Saudi industrial strategy documents used to contextualize implementation. The synthesis shows that predictive maintenance improves failure anticipation but requires disciplined data quality and maintenance workflows; OEE converts equipment losses into an operational performance language but can mislead when treated as an isolated utilization target; digital twins create a dynamic decision layer linking physical assets with simulation and prognostics; and Lean Six Sigma converts diagnostic insight into controlled, repeatable improvement. Their greatest value therefore emerges through integration rather than parallel deployment. The paper develops a closed-loop reliability-performance framework and a staged maturity roadmap for Saudi factories, emphasizing brownfield connectivity, criticality-based sensing, interoperable data architecture, workforce capability, cybersecurity, and value-based governance. The proposed approach supports higher asset availability, stable cycle performance, lower quality loss, and stronger local manufacturing capability while avoiding technology-led transformation without measurable operational return.