What type of oil should I use in my Ford Focus?

I just bought a used Ford Focus and I'm not sure what type of oil to use. I've heard different opinions from my friends and family. Can someone give me a definitive answer?

You should always use the recommended oil grade listed in your Ford Focus owner's manual. Using the wrong oil could cause engine damage and affect your car's performance.

My Ford Focus runs best with synthetic oil. It's a little more expensive, but it's worth it for the improved engine performance and longer oil change intervals.

I've tried different types of oil in my Ford Focus and have found that using full synthetic oil improves fuel efficiency and keeps the engine running smooth.