I noticed the 'Ford 455' remark and just let it slide. Typo, or whatever.....
I don't buy into the '20W-50 is the devil' argument, either. In very warm, southern climates, I'd imagine it will work fine for thousands of miles, as it has.
It just doesn't work very well in colder norther climates for much of the year...but even THAT isn't true. A 20W oil is cold-crank tested down to -15C. That means it could theoretically be used in a lot of Canada for all months of the year except December, January, and February. In most places, it's above -15C the rest of the year....