Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) are two technologies designed to improve fuel economy on the Chevrolet 5.3-liter V8. AFM, used in older engines, deactivates half of the cylinders under light load. While it saves fuel, it can increase oil consumption and stress lifters in the deactivated cylinders.

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DFM, introduced with the Ecotec3 series, is more advanced, allowing the engine to deactivate between one and seven cylinders depending on driving conditions. This system is smoother and more efficient, reducing some of the issues seen with AFM.

Both systems work to balance power and efficiency, but DFM generally offers better long-term reliability. Still, some owners prefer to disable either system to prevent lifter wear and avoid potential oil consumption problems.