The recommended motor oil for a 2003 Ford Ranger depends on the engine it has. Ford Rangers of that year came with several different engines. To know for sure, you need to check your owner's manual. The manual will specify the weight (e.g., 5W-30, 10W-30) and type (conventional, synthetic blend, or full synthetic) of oil recommended for your specific engine.
However, generally speaking, a 2003 Ford Ranger often used 5W-30 or 10W-30 weight oil. Whether conventional, synthetic blend, or full synthetic is acceptable will be detailed in your owner's manual. Always consult your owner's manual for the precise recommendation. Using the wrong oil can damage your engine.
