If anything the Motorcraft 5W-20 seems to be more shear stable than dino 5W-30's. They seem to shear down to a 20 in a few thousand miles. Whereas the Motorcraft 5W-20 stays a solid 20. That way you'll have less deposits in the oil. Plus it's a bargain for a quality oil
OK, sounds good. It is for a Ford Modular 4.6L speced for 5W-20 mustang driven hard. It is hot here, so I got 2 quarts motorcraft 5W-30 and 4 qt 5W-20 for a little piece of mind.