I just purchased a 2008 Focus SE. Wife and i are loving it. I just read something that i never read before - that the use of 5w30 is better for my car than 5w20. Even though 5w20 is recommended by Ford. I don't think I believe that. I am planning on using a synthetic 5w20 or MC syn blend 5w20. With a MC filter, or a Pure One. I'm thinking I should stay with the mfg recommendation of 5w20. Am I correct?[???