Car has 6K miles on it and will change to synthetic at 7K miles. Will use a 5K mile OCI. Planned on using Mobil 1 5w30. Is this the best oil for this engine. Would another oil or weight of Mobil 1 be better for a 5K mile OCI. I live in SW Missouri, summer 90's winters down to 0 degrees. Car is not driven that hard and most trips are over 15 miles each way.