What kind of oil does the 2003 Ford Focus take?

There were two different engine options offered on the 2003 Ford Focus. Your model may have come with either the 2.0L 4Cylinder engine, or the slightly larger 2.3L 4Cylinder. Luckily, for simplicity's sake, they require the same type and amount of oil. Whichever engine You have, You'll want to fill it with 4.5 quarts of SAE 5W-20 full synthetic motor oil. In a pinch, You can substitute out SAE 5W-30, though this isn't recommended, especially over long periods. The reason for this comes down to oil weight. Higher numbers mean a thicker oil, which can introduce friction into Your system. Over time, this will cause Your engine to work harder and less efficiently, which can lead to premature engine failure.