The military has striving for a "single fuel battlefield" so as to ease logistical support. All diesel engines in the military, like the Chevy engine in the Hummer, or the new 7 tons and all the generators and other diesels, run on Jet fuel. They try to stick with JP-8, but they can run JP-4 or 5 in a pinch. I know that the military doesn't put any additives in this jet fuel, but the newer motors are designed such that they do not require as much lubricity as our old ones like the 617s. The fuel pump chanbers in the 617s definitely need the extra lubricity in my opinion.
I drove around Iraq as a FAC in a 7 ton and we often fueled up at FARP locations with the same stuff put in Harriers and helicopters, allJP-8 (same as jet a+). It is possible to get this for free, but you have to follow aircraft that are about to shut down and catch the return fuel that gets dumped out in a bucket after shut-down.
Have fun, Adam