I live in the SW. Pretty hot here most of the summer, and I'm out in it, sometimes driving all day across west (uninhabited) Texas. Have driven this engine over 33,000 miles, & use Mobil 1 15-50. It has plenty of zddp, but you can add:
http://www.cam-shield.com/ if you like. I have a small block now, but used the same
oil in a FE when I had it with the same good results: no leaks, no measurable wear, no problems.
Z. Ray