For the Focus, I use the Motorcraft blend that came in the engine. I've tried synthetic and normal, the Ford blend seems to keep the engine quiet and happy. The Subaru gets full synthetic like it needs. I usually use Royal Purple since it's not much more than just plain synthetic, and it's usually derived from cleaner and actual synthetic stocks, unlike "synthetic" oil which can just be highly refined oil that's been cleaned up and had it's molecular structure changed.