The recommended motor oil for a 2005 Saturn Ion depends on the engine it has. The Ion came with a few different engines. To know for sure, you need to check your owner's manual. It will specify the correct viscosity (like 5W-30 or 10W-30) and the type of oil (conventional, synthetic blend, or full synthetic).
Generally, many 2005 Saturn Ions used 5W-30 oil, but always consult your owner's manual for the definitive answer. Using the wrong type or viscosity of oil can damage your engine.
