Fords interest is #1) getting the car past the warranty period and #2) satisfying the federal government standards in fuel economy. Therefore of course they will suggest 5W20 in naturally aspirated applications when they think they can get away with it. On turbo applications they say 5W30 when it probably should be like a Euro 5W40.
On a high miles engine like this one I wouldnt be putting in a 5W20 and probably wouldnt have put in a 5W20 even when new. I posted a while back about API SP rated Quaker State Euro 5W40. Its really a robust 5W30 rather then a true 5W40. It seemed to work well.
On a high miles engine like this one I wouldnt be putting in a 5W20 and probably wouldnt have put in a 5W20 even when new. I posted a while back about API SP rated Quaker State Euro 5W40. Its really a robust 5W30 rather then a true 5W40. It seemed to work well.