Your Ranger is a dog because the 3.0L Vulcan is a dog; it's underpowered by most any standard.
I can say that because I've owned a few, I still drive one now in my '97 Taurus, and I absolutely love them! They are a very easy engine to service, to do major work on, and they will run nearly forever with just a good routine maintenance plan. They don't need synthetic in any way to function properly for well past 250k miles.
The reason for this is that they are a well designed engine. I'm not implying that other brands don't have good designs, as many do. But Ford got this one right, overall. Great lube system, simple design, and the fact that it produces a relatively low HP/litre number probably helps; keeps the component stress down. In my mind, it is the modern v-6 equivilant to Ford's old 4.9L L-6; reknowned for its longevity, and "average at best" power levels.
The oils you've chosen will work quite well in your vehicles; I don't want to detract from the products you've selected. And I cannot comment on the Mitsu' as I've never had much real experience with one. But the Ranger/Vulcan will soldier on for another 100k or better, easily.
Your committment to good routine PM will benefit the Ranger much more than any anal-retentive obsession with a particular brand/grade of oil. That's kind of a buzz-kill to the whole BITOG mentality, but it's the truth at its core.