Should I add a front bumper air dam?

Good afternoon guys, as a lot of y'all have much more knowledge of our trucks and wisdom than I do I'd like y'all's opinion.

I have an air dam off of a 95 f150, well actually the entire bumper but I'm not concerned with the bumper. So my question is- Is it worth it to put an air dam/chin spoiler on our trucks? Any noticable mpg, cooling, other benefits? The OEMs do it so there has to be a reason.

I don't even know if the 95 one will be remotely close to fitting, but in general, is the concept worth testing?

It won't hurt.  Ford actually had a really small one on some of the trucks which were supposed to get better MPG, but it was only ~1" tall and I doubt did much.  However, I don't think the later one will fit.  I tried one from a '95 truck and it didn't come close to fitting.  But perhaps you will find one that will?