It’s the job of engine and gear oils to reduce friction between moving parts, protect against corrosion and keep components clean. By coming between and adhering to metal, the lubricants ensure the components effectively 'float' on a thin film of oil, preventing the metal-to-metal contact that causes friction, heat and wear. By preventing the build-up of dirt, and keeping engine parts clean and in good condition, lubricants can also help prevent corrosion and premature engine damage. The better the quality of the oil, the better its long-term ability to perform these functions, ultimately increasing the reliability and performance of the engine.